Monitoring circuit for photovoltaic module

ABSTRACT

A monitoring circuit for a photovoltaic module includes a measurement conditioning circuit, a microcontroller circuit, and a transmitter circuit. The measurement conditioning circuit includes a voltage sense terminal, a voltage reference terminal, and a digital measurement data output. The microcontroller circuit includes a digital measurement data input coupled with the digital measurement data output, a modulation clock input, a measurement data stream output, and a transmit select output. The transmitter circuit includes a measurement data stream input coupled with the measurement data stream output, a modulation clock output coupled with the modulation clock input, a transmit select input coupled with the transmit select output, and positive and negative output communication terminals.

Under 35 U.S.C. § 119, this application claims priority to, and thebenefit of, U.S. Provisional Patent Application Ser. No. 62/821,054,entitled “Integrated Module Level Monitoring for Photovoltaic Modules,”filed Mar. 20, 2019, the entirety of which is hereby incorporated byreference.

BACKGROUND

Monitoring the health of a photovoltaic (PV) system is currentlyperformed at the system level. This can determine the health of a stringof PV modules. The health of an individual PV module cannot bedetermined. Existing health monitoring techniques would require amonitoring system that operates independently of the PV system.Moreover, monitoring the health of an individual PV module usingcommercial off-the-shelf products is prohibitively expensive and powerintensive.

SUMMARY

According to one aspect, a monitoring circuit for a PV module includes ameasurement conditioning circuit, a microcontroller circuit, and atransmitter circuit. The measurement conditioning circuit includes avoltage sense terminal, a voltage reference terminal, and a digitalmeasurement data output. The microcontroller circuit includes a digitalmeasurement data input coupled with the digital measurement data output,a modulation clock input, a measurement data stream output, and atransmit select output. The transmitter circuit includes a measurementdata stream input coupled with the measurement data stream output, amodulation clock output coupled with the modulation clock input, atransmit select input coupled with the transmit select output, andpositive and negative output communication terminals.

In another aspect, a method for monitoring a PV module includesreceiving a sensed voltage signal at a voltage sense terminal of ameasurement conditioning circuit from a string of PV sub-modulesassociated with the PV module. The method also includes receiving avoltage reference signal at a voltage reference terminal of themeasurement conditioning circuit from the string of PV sub-modules. Themethod also includes generating digital measurement data at a digitalmeasurement data output of the measurement conditioning circuit based onthe sensed voltage signal in reference to the voltage reference signalsuch that the sensed voltage signal is represented within the digitalmeasurement data. The method also includes generating a modulation clocksignal at a modulation clock output of a transmitter circuit. The methodalso includes generating a measurement data stream at a measurement datastream output of a microcontroller circuit based on the digitalmeasurement data at a digital measurement data input and the modulationclock signal at a modulation clock input such that the sensed voltagesignal is represented within the measurement data stream. The methodalso includes generating an output communication signal at thetransmitter circuit based on the modulation clock signal and themeasurement data stream at a measurement data stream input such that thesensed voltage signal is represented within the output communicationsignal. The method also includes generating a transmit select signal ata transmit select output of the microcontroller circuit based on themeasurement data stream. The method also includes transmitting theoutput communication signal from the transmitter circuit to acommunication interface circuit via positive and negative outputcommunication terminals in response to the transmit select signal at atransmit select input of the transmitter circuit.

In another aspect, a PV module includes a communication interfacecircuit, a first PV sub-module, a second PV sub-module, a third PVsub-module, and a monitoring circuit. The communication interfacecircuit includes positive and negative input communication terminals andan external interface. The first PV sub-module includes positive andnegative DC power terminals. The second PV sub-module includes apositive DC power terminal coupled with the negative DC power terminalof the first PV sub-module and a negative DC power terminal. The thirdPV sub-module includes a positive DC power terminal coupled with thenegative DC power terminal of the second PV sub-module and a negative DCpower terminal. The monitoring circuit includes positive and negativeoutput communication terminals coupled with the positive and negativeinput communication terminals, a voltage sense terminal coupled with thepositive DC power terminal of the first PV sub-module, and a voltagereference terminal coupled with the negative DC power terminal of thethird PV sub-module.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an example of a monitoring circuit fora PV module.

FIG. 2 is a timing diagram of an example of the timing of select signalsshown in FIG. 1.

FIG. 3 is a schematic diagram of an example of a permission to operate(PTO) distribution circuit.

FIG. 4 is a schematic diagram of an example of a receiver circuit.

FIG. 5 is a schematic diagram of an example of a measurementconditioning circuit.

FIG. 6 is a timing diagram of an example of the timing of select signalsshown in FIG. 5.

FIG. 7 is a schematic diagram of another example of a measurementconditioning circuit.

FIG. 8 is a schematic diagram of an example of a transmitter circuit.

FIG. 9 is a flow chart for an example of a method for monitoring a PVmodule.

FIG. 10 is a flow chart for another example of a method for monitoring aPV module.

FIG. 11 is a flow chart for another example of a method for monitoring aPV module.

FIG. 12 is a flow chart for another example of a method for monitoring aPV module.

FIG. 13 is a flow chart for another example of a method for monitoring aPV module.

FIG. 14 is a flow chart for another example of a method for monitoring aPV module.

FIG. 15A-15C is a flow chart for another example of a method formonitoring a PV module.

FIG. 16 is a flow chart for another example of a method for monitoring aPV module.

FIG. 17 is a schematic diagram of an example of a PV module.

FIG. 18 is a schematic diagram of another example of a PV module.

FIG. 19 is a schematic diagram of another example of a PV module.

FIG. 20 is a schematic diagram of another example of a PV module.

FIG. 21 is a schematic diagram of another example of a PV module.

FIG. 22 is a schematic diagram of another example of a PV module.

DETAILED DESCRIPTION

In the drawings, like reference numerals refer to like elementsthroughout, and the various features are not necessarily drawn to scale.In the following discussion and in the claims, the terms “including”,“includes”, “having”, “has”, “with”, or variants thereof are intended tobe inclusive in a manner like the term “comprising”, and thus should beinterpreted to mean “including, but not limited to.” Also, the terms“couple” or “couples” or “coupled” includes indirect or directelectrical or mechanical connection or combinations thereof. Forexample, if a first device couples to or is coupled with a seconddevice, that connection may be through a direct electrical connection,or through an indirect electrical connection via one or more interveningdevices and connections. One or more operational characteristics ofvarious circuits, systems and/or components are hereinafter described inthe context of functions which in some cases result from configurationand/or interconnection of various structures when circuitry is poweredand operating.

FIG. 1 shows an example of a PV module 100 and an example of amonitoring circuit 102 for the PV module 100. The monitoring circuit 102includes a measurement conditioning circuit 104, a microcontrollercircuit 106, and a transmitter circuit 108. The measurement conditioningcircuit 104 includes a voltage sense terminal 110, a voltage referenceterminal 112, and a digital measurement data output 114. Themicrocontroller circuit 106 includes a digital measurement data input118 coupled with the digital measurement data output 114, a modulationclock input 120, a measurement data stream output 122, and a transmitselect output 124. The transmitter circuit 108 includes a measurementdata stream input 126 coupled with the measurement data stream output122, a modulation clock output 128 coupled with the modulation clockinput 120, a transmit select input 130 coupled with the transmit selectoutput 124, and positive and negative output communication terminals132, 134.

The measurement conditioning circuit 104 receives a sensed voltagesignal SENSED V at the voltage sense terminal 110 from a string of PVsub-modules 116 associated with the PV module 100. The measurementconditioning circuit 104 receives a voltage reference signal at thevoltage reference terminal 112 from the string of PV sub-modules 116.The measurement conditioning circuit 104 generates digital measurementdata DIG MEAS DATA at the digital measurement data output 114 based onthe sensed voltage signal SENSED V at the voltage sense terminal 110 inreference to the voltage reference signal at the voltage referenceterminal 112 such that the sensed voltage signal SENSED V is representedwithin the digital measurement data DIG MEAS DATA.

The microcontroller circuit 106 generates a measurement data stream MEASDATA STREAM at the measurement data stream output 122 based on thedigital measurement data DIG MEAS DATA at the digital measurement datainput 118 and a modulation clock signal MOD CLK at the modulation clockinput 120 such that the sensed voltage signal SENSED V is representedwithin the measurement data stream MEAS DATA STREAM. The microcontrollercircuit 106 generates a transmit select signal XMIT SELECT at thetransmit select output 124 based on the measurement data stream MEASDATA STREAM. The transmitter circuit 108 generates the modulation clocksignal MOD CLK at the modulation clock output 128. The transmittercircuit 108 generates an output communication signal COMM SIG OUT basedon the modulation clock signal MOD CLK and the measurement data streamMEAS DATA STREAM at the measurement data stream input 126 such that thesensed voltage signal SENSED V is represented within the outputcommunication signal COMM SIG OUT. The transmitter circuit 108 transmitsthe output communication signal COMM SIG OUT to a communicationinterface circuit 136 via the positive and negative output communicationterminals 132, 134 in response to the transmit select signal XMIT SELECTat the transmit select input 130.

In one example, the measurement conditioning circuit 104,microcontroller circuit 106, and transmitter circuit 108 are included inan integrated circuit (IC). In another example, the PV module 100includes the monitoring circuit 102.

In another example, the string of PV sub-modules 116 includes first andsecond PV sub-modules 1702, 1704/1706 (e.g., FIG. 17). In oneimplementation, the first PV sub-module 1702 includes the monitoringcircuit 102. In another implementation, the second PV sub-module1704/1706 includes the monitoring circuit 102. In anotherimplementation, the first PV sub-module 1702 includes a positive DCpower terminal 1714 and the second PV sub-module 1704/1706 includes anegative DC power terminal 1724/1730. The measurement conditioningcircuit 104 is receives the sensed voltage signal SENSED V from thepositive DC power terminal 1714 of the first PV sub-module 1702 via thevoltage sense terminal 110. The measurement conditioning circuit 104receives the voltage reference signal from the negative DC powerterminal 1724/1730 of the second PV sub-module 1704/1706 via the voltagereference terminal 112.

In another example, the measurement data stream MEAS DATA STREAMincludes a first representation of the digital measurement data DIG MEASDATA in data burst form for a first frequency of a spread frequencyshift keying (S-FSK) modulation scheme and a second representation ofthe digital measurement data DIG MEAS DATA in data burst form for asecond frequency of the S-FSK modulation scheme. In one implementation,the output communication signal COMM SIG OUT carries modulated datarepresenting the first and second representations of the digitalmeasurement data DIG MEAS DATA using the first and second frequencies ofthe S-FSK modulation scheme. In one example, the output communicationsignal COMM SIG OUT is compliant with PLC protocol requirements ofSunSpec Interoperability Specification, Communication Signal for RapidShutdown, Version 34. The microcontroller circuit 106 and thetransmitter circuit 108 are integrated to transmit the outputcommunication signal COMM SIG OUT carrying modulated data representingthe digital measurement data DIG MEAS DATA during a zero energy periodof a repetitive data frame specified in the PLC protocol requirements ofthe SunSpec Interoperability Specification.

In another example, the microcontroller circuit 106 uses the modulationclock signal MOD CLK to sample the digital measurement data DIG MEASDATA to form the measurement data stream MEAS DATA STREAM. In anotherexample, the transmitter circuit 108 uses the modulation clock signalMOD CLK to sample the measurement data stream MEAS DATA STREAM to formthe output communication signal COMM SIG OUT.

In another example, the monitoring circuit 102 of FIG. 1 also includes areceiver circuit 142. The microcontroller circuit 106 also includes aninput communication data stream input 138 and a demodulation clock input140. The receiver circuit 142 includes positive and negative inputcommunication terminals 144, 146, an input communication data streamoutput 148 coupled with the input communication data stream input 138,and a demodulation clock output 150 coupled with the demodulation clockinput 140. The receiver circuit 142 receives an input communicationsignal COMM SIG IN at the positive and negative input communicationterminals 144, 146 from the communication interface circuit 136. Thereceiver circuit 142 generates a demodulation clock signal DEMOD CLK atthe demodulation clock output 150. The receiver circuit 142 generates aninput communication data stream INPUT COMM DATA STREAM at the inputcommunication data stream output 148 based on the input communicationsignal COMM SIG IN at the positive and negative input communicationterminals 144, 146 and the demodulation clock signal DEMOD CLK. Themicrocontroller circuit 106 receives the input communication data streamINPUT COMM DATA STREAM from the receiver circuit 142 at the inputcommunication data stream input 138. The microcontroller circuit 106receives the demodulation clock signal DEMOD CLK from the receivercircuit 142 at the demodulation clock input 140. The microcontrollercircuit 106 processes the input communication data stream INPUT COMMDATA STREAM using the demodulation clock signal DEMOD CLK to detectmodulated data carried by the input communication signal COMM SIG IN andrepresented within the input communication data stream INPUT COMM DATASTREAM. The microcontroller circuit 106 generates the transmit selectsignal XMIT SELECT in response to detecting, for a predetermined time,an absence of the modulated data in the input communication data streamINPUT COMM DATA STREAM representing the input communication signal COMMSIG IN. In another example, the measurement conditioning circuit 104,microcontroller circuit 106, transmitter circuit 108, and receivercircuit 142 are included in an integrated circuit.

In another example, the input communication signal COMM SIG IN is basedon a power line communication (PLC) signal associated with the PV module100. The communication interface circuit 136 receives the PLC signalfrom a remote transmitter circuit 1806 via a DC bus 1720 (e.g., FIG. 17)associated with the PV module 100. The input communication signal COMMSIG IN is based on data carried by the PLC signal transmitted via the DCbus 1720. In one implementation, the PLC signal is a spread frequencyshift keying waveform. In one example, the S-FSK waveform is compliantwith the PLC protocol requirements of SunSpec InteroperabilitySpecification, Communication Signal for Rapid Shutdown, Version 34, andthe data carried by the PLC signal during an active period of arepetitive data frame includes commands compliant with code requirementsof the SunSpec Interoperability Specification.

In another example, the input communication signal COMM SIG IN is basedon a wireless communication signal associated with the PV module 100.The communication interface circuit 136 receives the wirelesscommunication signal from a remote transmitter circuit 1904 (e.g., FIG.19). The input communication signal COMM SIG IN is based on data carriedby the wireless communication signal.

In another example, the input communication signal COMM SIG IN is basedon a wired control line communication signal associated with the PVmodule 100. The communication interface circuit 136 receives the wiredcontrol line communication signal from a remote receiver/transmittercircuit 2006 (e.g., FIG. 20) via a wired control line. The inputcommunication signal COMM SIG IN is based on data carried by the wiredcontrol line communication signal.

In another example, the receiver circuit 142 uses the demodulation clocksignal DEMOD CLK to sample the input communication signal COMM SIG IN toform the input communication data stream INPUT COMM DATA STREAM. Inanother example, the microcontroller circuit 106 uses the demodulationclock signal DEMOD CLK to demodulate data carried by the inputcommunication data stream INPUT COMM DATA STREAM.

In another example, the monitoring circuit of FIG. 1 also includes a PTOdistribution circuit 154. The microcontroller circuit 106 also includesa PTO output 152. The PTO distribution circuit 154 includes a PTO input156 coupled with the PTO output 152, a local PTO output terminal 158,and a remote PTO output terminal 160. The microcontroller circuit 106generates a PTO signal PTO at the PTO output 152 in response todetecting a presence of modulated data carried by the inputcommunication signal COMM SIG IN and represented within the inputcommunication data stream INPUT COMM DATA STREAM that represents a keepalive command associated with the PV module 100. The PTO distributioncircuit 154 generates a local PTO signal LOCAL PTO at the local PTOoutput terminal 158 based on the PTO signal PTO at the PTO input 156.The PTO distribution circuit 154 generates a remote PTO signal REMOTEPTO at the remote PTO output terminal 160 based on the PTO signal PTO.In another example, the measurement conditioning circuit 104,microcontroller circuit 106, transmitter circuit 108, receiver circuit142, and PTO distribution circuit 154 are included in an integratedcircuit.

In another example, the string of PV modules includes a PV sub-module1702 (e.g., FIG. 17). The PTO distribution circuit 154 provides thelocal PTO signal LOCAL PTO to a sub-module controller circuit 162associated with the PV sub-module 1702. In another example, the PTOdistribution circuit 154 provides the remote PTO signal REMOTE PTO to ashutdown initiation device 164 associated with the PV module 100. Inanother example, the input communication signal COMM SIG IN is based ona PLC signal associated with the PV module 100 that is compliant withthe PLC protocol requirements of SunSpec Interoperability Specification,Communication Signal for Rapid Shutdown, Version 34, and the modulateddata representing the keep alive command is compliant with permission tooperate code requirements of the SunSpec Interoperability Specification.

FIG. 2 shows a timing diagram 200 of an example of the timing of selectsignals in FIG. 1 in relation to operation of the monitoring circuit102. The timing diagram 200 reflects a simplified scenario for a PVmodule 100 that is stationary during which the signals are stable andreflect normal conditions. The monitoring circuit 102 and PV sub-modules116 generally experience this scenario during daylight hours with minorday-to-day and seasonal changes based on actual environmentalconditions. In other examples, the amount of light received by the PVsub-modules 116 during daylight hours may vary based on dust, dirt,debris, snow, ice, rain, clouds, shade, or other conditions that cause aportion of light that would otherwise reach one or more of the PVsub-modules 116 to be filtered or blocked. In other examples, the PVmodule 100 tracks the sun or is otherwise adjusted to follow the sun inrelation to a daily cycle. In these examples, the select signals wouldbe different but react to environmental conditions in a similar mannerto that described herein for the stationary PV sub-module.

A curve 202 shows an example of the sensed voltage signal SENSED Vreceived by the measurement conditioning circuit 104 from the string ofPV sub-modules 116. The sensed voltage signal SENSED V is shown at 100percent to reflect a condition during daylight hours with full exposureof the to the PV sub-modules 116 to light. For example, the 100 percentlevel may represent 60 volts DC. In one implementation, the sensedvoltage signal SENSED V varies over daylight hours due to numerousfactors (e.g., rain, clouds, etc.) and may exhibit curves and smoothstransitions rather than the linear signal shown in FIG. 2. In otherexamples, the sensed voltage signal SENSED V may be lower when the PVsub-modules 116 are not fully exposed to the sun. For example, thesensed voltage signal SENSED V drops to zero (0) percent after sunsetuntil sunrise.

A curve 204 shows an example of the input communication signal COMM SIGIN received by the receiver circuit 142 from the communication interfacecircuit 136. In this example, the input communication signal COMM SIG INincludes a waveform with modulated input data during an active period T1of a repetitive data frame T2. The repetitive data frame T2 alsoincludes a zero energy period T3 during which no data is modulated onthe input communication signal COMM SIG IN. In one example, themodulated input data includes a command associated with operation of thePV module 100. The command being compliant with code requirements of apredetermined command protocol. In one implementation, the inputcommunication signal COMM SIG IN may include a residual noise level andthe waveform and modulated data may exhibit curves and smoothtransitions rather than the linear portions and sharp transitions. Inanother example, the PV system may be experiencing conditions thatresult in the absence of the modulated input data during the activeperiod T1.

A curve 206 shows an example of the transmit select signal XMIT SELECTgenerated by the microcontroller circuit 106 and provided to thetransmitter circuit 108. The transmit select signal XMIT SELECT is adigital signal that varies between “OFF” and “ON” conditions. Themicrocontroller circuit 106 varies the transmit select signal XMITSELECT between the “OFF” and “ON” conditions to form a pulsed signal.The microcontroller circuit 106 transitions the transmit select signalXMIT SELECT from the “OFF” condition to the “ON” condition in responseto detecting, for a predetermined time T4, an absence of modulated datain the input communication data stream INPUT COMM DATA STREAMrepresenting the input communication signal COMM SIG IN. The period T5of time the transmit select signal XMIT SELECT is “ON” overlaps most ofthe zero energy period of the data frame T2. The predetermined time T4associated with detecting the absence of modulated data reflects a lagbetween the start of the zero energy period T3 and the start of theperiod T5 when the transmit select signal XMIT SELECT is “ON.” Themicrocontroller circuit 106 transitions the transmit select signal XMITSELECT from the “ON” condition to the “OFF” condition in response todetecting modulated data in the input communication data stream INPUTCOMM DATA STREAM representing the input communication signal COMM SIGIN. The period T6 of time the transmit select signal XMIT SELECT is “ON”that overlaps the active period T1 of the next data frame T2 reflects alag between the start of the next active period T1 and the start of thenext period when the transmit select signal XMIT SELECT is “OFF.” In oneimplementation, the transmit select signal XMIT SELECT includes aresidual noise level and may exhibit curves and smooth transitionsrather than the linear portions with sharp transitions.

A curve 208 shows an example of the output communication signal COMM SIGOUT generated by the transmitter circuit 108 and provided to thecommunication interface circuit 136. In this example, the outputcommunication signal COMM SIG IN includes a waveform with modulatedoutput data during the period T5 when the transmit select signal XMITSELECT is “ON.” In one example, the modulated output data includes databursts associated with the sensed voltage signal SENSED V. The databursts being compliant with code requirements of a predetermined dataprotocol. In one implementation, the output communication signal COMMSIG OUT may include a residual noise level and the waveform andmodulated data may exhibit curves and smooth transitions rather than thelinear portions and sharp transitions. In other examples, there may beless data bursts or more data bursts during the period T5 when thetransmit select signal XMIT SELECT is “ON.”

A curve 210 shows an example of the local PTO signal LOCAL PTO generatedby the PTO distribution circuit 154 and provided to one or moresub-module controller circuits 162 associated with the string of PVsub-modules 116. The local PTO signal LOCAL PTO is a digital signal thatvaries between “OFF” and “ON” conditions. The PTO distribution circuit154 generates the local PTO signal LOCAL PTO based on the PTO signal PTOreceived from the microcontroller circuit 106. The microcontrollercircuit 106 generates the PTO signal PTO in response to detecting apresence of modulated input data carried by the input communicationsignal COMM SIG IN and represented within the input communication datastream INPUT COMM DATA STREAM. In one example, the modulated input datadetected by the microcontroller circuit 106 represents a keep alivecommand associated with the PV module 100. The command being compliantwith code requirements of a predetermined command protocol. For example,if the microcontroller circuit 106 detects the keep alive command duringthe active period T1 of repetitive data frames T2, the PTO signal PTO isactivated and the local PTO signal LOCAL PTO signal remains in the “ON”condition. If the microcontroller circuit 106 detects the absence of thekeep alive command for a predetermined amount of data frames T2, the PTOsignal PTO is deactivated and the local PTO signal LOCAL PTO signaltransitions from the “ON” condition to the “OFF” condition. In oneimplementation, the local PTO signal LOCAL PTO signal may include aresidual noise level and may exhibit curves and smooth transitionsrather than the linear portion shown in FIG. 2.

FIG. 3 shows an example of the PTO distribution circuit 154. The PTOdistribution circuit 154 includes a local PTO amplifier circuit 310 anda remote PTO amplifier circuit 312. The local PTO amplifier circuit 310includes a first PTO input 314 coupled with the PTO output 152 and thelocal PTO output terminal 158 of the PTO distribution circuit 154. Theremote PTO amplifier circuit 312 includes a second PTO input 316 coupledwith the PTO output 152 and the remote PTO output terminal 160 of thePTO distribution circuit 154. The local PTO amplifier circuit 310generates the local PTO signal LOCAL PTO at the local PTO outputterminal 158 based on the PTO signal PTO at the first PTO input 314. Theremote PTO amplifier circuit 312 generates the remote PTO signal REMOTEPTO at the remote PTO output terminal 160 based on the PTO signal PTO atthe second PTO input 316. The PTO input 156 of the PTO distributioncircuit 154 includes the first and second PTO inputs 314, 316.

FIG. 4 shows an example of the receiver circuit 142. The receivercircuit 142 includes a bandpass filter circuit 410, a crystal oscillatorcircuit 412, and an analog-to-digital converter circuit 414. Thebandpass filter circuit 410 includes the positive and negative inputcommunication terminals 144, 146 of the receiver circuit 142 and afiltered input communication output 416. The crystal oscillator circuit412 includes the demodulation clock output 150 of the receiver circuit142. The analog-to-digital converter circuit 414 includes a filteredinput communication input 418 coupled with the filtered inputcommunication output 416, a second demodulation clock input 420 coupledwith the demodulation clock output 150, and the input communication datastream output 148 of the receiver circuit 142. The bandpass filtercircuit 410 generates a filtered input waveform FILTERED INPUT WAVEFORMat the filtered input communication output 416 based on the inputcommunication signal COMM SIG IN at the positive and negative inputcommunication terminals 144, 146. The crystal oscillator circuit 412generates the demodulation clock signal DEMOD CLK at the demodulationclock output 150. The analog-to-digital converter circuit 414 generatesthe input communication data stream INPUT COMM DATA STREAM at the inputcommunication data stream output 148 based on the filtered inputwaveform FILTERED INPUT WAVEFORM at the filtered input communicationinput 418 in response to the demodulation clock signal DEMOD CLK at thesecond demodulation clock input 420. In another example, theanalog-to-digital converter circuit 414 uses the demodulation clocksignal DEMOD CLK to sample the filtered input waveform FILTERED INPUTWAVEFORM to form the input communication data stream INPUT COMM DATASTREAM. In another example, the bandpass filter circuit 410 receives theinput communication signal COMM SIG IN from the communication interfacecircuit 136.

FIG. 5 shows an example of the measurement conditioning circuit 104. Themeasurement conditioning circuit 104 includes a voltage measurementconditioning circuit 510 and an analog-to-digital converter circuit 512.The voltage measurement conditioning circuit 510 includes the voltagesense terminal 110 of the measurement conditioning circuit 104, thevoltage reference terminal 112 of the measurement conditioning circuit104, and an analog voltage output 514. The analog-to-digital convertercircuit 512 includes an analog voltage input 516 coupled with the analogvoltage output 514 and a digital voltage measurement output 518 coupledwith a digital voltage measurement input 520 of the microcontrollercircuit 106. The voltage measurement conditioning circuit 510 receivesthe sensed voltage signal SENSED V at the voltage sense terminal 110from the string of PV sub-modules 116. The voltage measurementconditioning circuit 510 receives the voltage reference signal at thevoltage reference terminal 112 from the string of PV sub-modules 116.The voltage measurement conditioning circuit 510 generates an analogvoltage signal ANALOG V at the analog voltage output 514 based on thesensed voltage signal SENSED V at the voltage sense terminal 110 inreference to the voltage reference signal at the voltage referenceterminal 112. The analog-to-digital converter circuit 512 generatesdigital voltage measurement data DIG V MEAS DATA at the digital voltagemeasurement output 518 based on the analog voltage signal ANALOG V atthe analog voltage input 516 such that the sensed voltage signal SENSEDV is represented within the digital voltage measurement data DIG V MEASDATA. The digital measurement data output 114 of the measurementconditioning circuit 104 includes the digital voltage measurement output518 and the digital measurement data DIG MEAS DATA generated by themeasurement conditioning circuit 104 includes the digital voltagemeasurement data DIG V MEAS DATA. The digital measurement data input 118of the microcontroller circuit 106 includes the digital voltagemeasurement input 520. In one implementation, the string of PVsub-modules 116 includes first and second PV sub-modules 1702, 1704/1706(e.g., FIG. 17). The first PV sub-module 1702 includes a positive DCpower terminal 1714 and the second PV sub-module 1704/1706 includes anegative DC power terminal 1724/1730. The voltage measurementconditioning circuit 510 receives the sensed voltage signal SENSED Vfrom the positive DC power terminal 1714 of the first PV sub-module 1702via the voltage sense terminal 110. The voltage measurement conditioningcircuit 510 receives the voltage reference signal from the negative DCpower terminal 1724/1730 of the second PV sub-module 1704/1706 via thevoltage reference terminal 112.

In another example, the voltage measurement conditioning circuit 510also includes a second voltage sense terminal 522 and a second analogvoltage output 524 and the measurement conditioning circuit 104 alsoincludes a second analog-to-digital converter circuit 526. The secondanalog-to-digital converter circuit 526 includes a second analog voltageinput 528 coupled with the second analog voltage output 524 and a seconddigital voltage measurement output 530 coupled with a second digitalvoltage measurement input 532 of the microcontroller circuit 106. Thevoltage measurement conditioning circuit 510 receives a second sensedvoltage signal SENSED V2 at the second voltage sense terminal 522 fromthe string of PV sub-modules 116. The voltage measurement conditioningcircuit 510 generates a second analog voltage signal ANALOG V2 at thesecond analog voltage output 524 based on the second sensed voltagesignal SENSED V2 at the second voltage sense terminal 522 in referenceto the voltage reference signal at the voltage reference terminal 112.The second analog-to-digital converter circuit 526 generates seconddigital voltage measurement data DIG V2 MEAS DATA at the second digitalvoltage measurement output 530 based on the second analog voltage signalANALOG V2 at the second analog voltage input 528 such that the secondsensed voltage signal SENSED V2 is represented within the second digitalvoltage measurement data DIG V2 MEAS DATA. The digital measurement dataoutput 114 of the measurement conditioning circuit 104 includes thesecond digital voltage measurement output 530 and the digitalmeasurement data DIG MEAS DATA generated by the measurement conditioningcircuit 104 includes the second digital voltage measurement data DIG V2MEAS DATA. The digital measurement data input 118 of the microcontrollercircuit 106 includes the second digital voltage measurement input 532.

In one implementation, the string of PV sub-modules 116 includes firstand second PV sub-modules 1702, 1704/1706 (e.g., FIG. 17). The first PVsub-module 1702 includes a positive DC power terminal 1714 and thesecond PV sub-module 1704/1706 includes a positive DC power terminal1722/1728 and a negative DC power terminal 1724/1730. The voltagemeasurement conditioning circuit 510 receives the sensed voltage signalSENSED V from the positive DC power terminal 1714 of the first PVsub-module 1702 via the voltage sense terminal 110. The voltagemeasurement conditioning circuit 510 receives the second sensed voltagesignal SENSED V2 from the positive DC power terminal 1722/1728 of thesecond PV sub-module 1704/1706 via the second voltage sense terminal522. The voltage measurement conditioning circuit 510 receives thevoltage reference signal from the negative DC power terminal 1724/1730of the second PV sub-module 1704/1706 via the voltage reference terminal112.

In another example, the voltage measurement conditioning circuit 510also includes a third voltage sense terminal 534 and a third analogvoltage output 536 and the measurement conditioning circuit 104 alsoincludes a third analog-to-digital converter circuit 538. The thirdanalog-to-digital converter circuit 538 includes a third analog voltageinput 540 coupled with the third analog voltage output 536 and a thirddigital voltage measurement output 542 coupled with a third digitalvoltage measurement input 544 of the microcontroller circuit 106. Thevoltage measurement conditioning circuit 510 receives a third sensedvoltage signal SENSED V3 at the third voltage sense terminal 534 fromthe string of PV sub-modules 116. The voltage measurement conditioningcircuit 510 generates a third analog voltage signal ANALOG V3 at thethird analog voltage output 536 based on the third sensed voltage signalSENSED V3 at the third voltage sense terminal 534 in reference to thevoltage reference signal at the voltage reference terminal 112. Thethird analog-to-digital converter circuit 538 generates third digitalvoltage measurement data DIG V3 MEAS DATA at the third digital voltagemeasurement output 542 based on the third analog voltage signal ANALOGV3 at the third analog voltage input 540 such that the third sensedvoltage signal SENSED V3 is represented within the third digital voltagemeasurement data DIG V3 MEAS DATA. The digital measurement data output114 of the measurement conditioning circuit 104 includes the thirddigital voltage measurement output 542 and the digital measurement dataDIG MEAS DATA generated by the measurement conditioning circuit 104includes the third digital voltage measurement data DIG V3 MEAS DATA.The digital measurement data input 118 of the microcontroller circuit106 includes the third digital voltage measurement input 544.

In one implementation, the string of PV sub-modules 116 includes first,second, and third PV sub-modules 1702, 1704, 1706 (FIG. 17). The firstPV sub-module 1702 includes a positive DC power terminal 1714, thesecond PV sub-module 1704 includes a positive DC power terminal 1722,and the third PV sub-module 1706 includes a positive DC power terminal1728 and a negative DC power terminal 1730. The voltage measurementconditioning circuit 510 receives the sensed voltage signal SENSED Vfrom the positive DC power terminal 1714 of the first PV sub-module 1702via the voltage sense terminal 110. The voltage measurement conditioningcircuit 510 receives the second sensed voltage signal SENSED V2 from thepositive DC power terminal 1722 of the second PV sub-module 1704 via thesecond voltage sense terminal 522. The voltage measurement conditioningcircuit 510 receives the third sensed voltage signal SENSED V3 from thepositive DC power terminal 1728 of the third PV sub-module 1706 via thethird voltage sense terminal 534. The voltage measurement conditioningcircuit 510 receives the voltage reference signal from the negative DCpower terminal 1730 of the third PV sub-module 1706 via the voltagereference terminal 112. In another implementation, the analog-to-digitalconverter circuit 512 includes the second and third analog-to-digitalconverter circuits 526, 538.

In another example, the measurement conditioning circuit 104 alsoincludes a current measurement conditioning circuit 546 and a secondanalog-to-digital converter circuit 548. The current measurementconditioning circuit 546 includes positive and negative current senseterminals 550, 552 and an analog current output 554. The secondanalog-to-digital converter circuit 548 includes an analog current input558 coupled with the analog current output 554 and a digital currentmeasurement output 560 coupled with a digital current measurement input562 of the microcontroller circuit 106. The current measurementconditioning circuit 546 receives a sensed current signal SENSED I atthe positive current sense terminal 550 from a current sensor 556associated with the string of PV sub-modules 116. The currentmeasurement conditioning circuit 546 receives a current reference signalat the negative current sense terminal 552 from the current sensor 556.The current measurement conditioning circuit 546 generates an analogcurrent signal ANALOG I at the analog current output 554 based on thesensed current signal SENSED I at the positive current sense terminal550 in reference to the current reference signal at the negative currentsense terminal 552. The second analog-to-digital converter circuit 548generates digital current measurement data DIG I MEAS DATA at thedigital current measurement output 560 based on the analog currentsignal ANALOG I at the analog current input 558 such that the sensedcurrent signal SENSED I is represented within the digital currentmeasurement data DIG I MEAS DATA. The digital measurement data output114 of the measurement conditioning circuit 104 includes the digitalcurrent measurement output 560 and the digital measurement data DIG MEASDATA generated by the measurement conditioning circuit 104 includes thedigital current measurement data DIG I MEAS DATA. The digitalmeasurement data input 118 of the microcontroller circuit 106 includesthe digital current measurement input 562.

In another example, the string of PV sub-modules 116 includes a positiveDC power terminal 1714 (FIG. 17) coupled with a positive DC power line1718 of a DC bus 1720 and a negative DC power terminal 1730 coupled witha negative DC power line 1732 of the DC bus 1720. The current sensor 556senses current passing through the string of PV sub-modules 116 betweenthe positive DC power line 1718 and the negative DC power line 1732. Thecurrent sensor 556 generates the sensed current signal SENSED I based onthe sensed current. The current sensor 556 includes positive andnegative terminals. The positive current sense terminal 550 of thecurrent measurement conditioning circuit 546 is coupled with thepositive terminal and the negative current sense terminal 552 of thecurrent measurement conditioning circuit 546 is coupled with thenegative terminal. In one implementation, the current sensor 556 sensescurrent passing through the positive DC power line 1718 between the DCbus 1720 and the positive DC power terminal 1714 of the string of PVsub-modules 116. In another implementation, the current sensor 556senses current passing through the negative DC power line 1732 betweenthe negative DC power terminal 1730 of the string of PV sub-modules 116and the DC bus 1720.

In another example, the microcontroller circuit 106 generates powermeasurement data associated with the string of PV sub-modules 116 basedon the digital voltage measurement data DIG V MEAS DATA associated withthe sensed voltage signal SENSED V and the digital current measurementdata DIG I MEAS DATA associated with the sensed current signal SENSED I.The measurement data stream MEAS DATA STREAM is also based on the powermeasurement data such that the power measurement data is representedwithin the measurement data stream MEAS DATA STREAM and the outputcommunication signal COMM SIG OUT.

In another example, the current measurement conditioning circuit 546also includes a second positive current sense terminal 564, a secondnegative current sense terminal 566, and a second analog current output568 and the measurement conditioning circuit 104 also includes a thirdanalog-to-digital converter circuit 572. The third analog-to-digitalconverter circuit 572 includes a second analog current input 574 coupledwith the second analog current output 568 and a second digital currentmeasurement output 576 coupled with a second digital current measurementinput 578 of the microcontroller circuit 106. The current measurementconditioning circuit 546 receives a second sensed current signal SENSEDI2 at the second positive current sense terminal 564 from a secondcurrent sensor 570 associated with the string of PV sub-modules 116. Thecurrent measurement conditioning circuit 546 receives a second currentreference signal at the second negative current sense terminal 566 fromthe second current sensor 570. The current measurement conditioningcircuit 546 generates a second analog current signal ANALOG I2 at thesecond analog current output 568 based on the second sensed currentsignal SENSED I2 at the second positive current sense terminal 564 inreference to the second current reference signal at the second negativecurrent sense terminal 566. The third analog-to-digital convertercircuit 572 generates second digital current measurement data DIG I2MEAS DATA at the second digital current measurement output 576 based onthe second analog current signal ANALOG I2 at the second analog currentinput 574 such that the second sensed current signal SENSED I2 isrepresented within the second digital current measurement data DIG I2MEAS DATA. The digital measurement data output 114 of the measurementconditioning circuit 104 includes the second digital current measurementoutput 576 and the digital measurement data DIG MEAS DATA generated bythe measurement conditioning circuit 104 includes the second digitalcurrent measurement data DIG I2 MEAS DATA. The digital measurement datainput 118 of the microcontroller circuit 106 includes the second digitalcurrent measurement input 578. In one implementation, theanalog-to-digital converter circuit 512 includes the second and thirdanalog-to-digital converter circuits 548, 572.

In another example, the string of PV sub-modules 116 includes a positiveDC power terminal 1714 (FIG. 17) coupled with a positive DC power line1718 of a DC bus 1720 and a negative DC power terminal 1730 coupled witha negative DC power line 1732 of the DC bus 1720. In one implementation,the current sensor 556 includes positive and negative terminals. Thepositive current sense terminal 550 of the current measurementconditioning circuit 546 is coupled with the positive terminal and thenegative current sense terminal 552 of the current measurementconditioning circuit 546 is coupled with the negative terminal. Thecurrent sensor 556 senses current passing through the positive DC powerline 1718 between the DC bus 1720 and the positive DC power terminal1714 of the string of PV sub-modules 116. The current sensor 556generates the sensed current signal SENSED I based on the sensedcurrent. In another implementation, the second current sensor 570includes second positive and negative terminals. The second positivecurrent sense terminal 564 of the current measurement conditioningcircuit 546 is coupled with the second positive terminal and the secondnegative current sense terminal 566 of the current measurementconditioning circuit 546 is coupled with the second negative terminal.The second current sensor 570 senses current passing through thenegative DC power line 1732 between the negative DC power terminal 1730of the string of PV sub-modules 116 and the DC bus 1720. The secondcurrent sensor 570 generates the second sensed current signal SENSED I2based on the sensed current.

In another example, the measurement conditioning circuit 104 alsoincludes a temperature measurement conditioning circuit 580 and a secondanalog-to-digital converter circuit 582. The temperature measurementconditioning circuit 580 includes positive and negative temperaturesense terminals 584, 586 and an analog temperature output 588. Thesecond analog-to-digital converter circuit 582 includes an analogtemperature input 592 coupled with the analog temperature output 588 anda digital temperature measurement output 594 coupled with a digitaltemperature measurement input 596 of the microcontroller circuit 106.The temperature measurement conditioning circuit 580 receives a sensedtemperature signal SENSED T at the positive temperature sense terminal584 from a temperature sensor 590 associated with the string of PVsub-modules 116. The temperature measurement conditioning circuit 580receives a temperature reference signal at the negative temperaturesense terminal 586 from the temperature sensor 590. The temperaturemeasurement conditioning circuit 580 generates an analog temperaturesignal ANALOG T at the analog temperature output 588 based on the sensedtemperature signal SENSED T at the positive temperature sense terminal584 in reference to the temperature reference signal at the negativetemperature sense terminal 586. The second analog-to-digital convertercircuit 582 generates digital temperature measurement data DIG T MEASDATA at the digital temperature measurement output 594 based on theanalog temperature signal ANALOG T at the analog temperature input 592such that the sensed temperature signal SENSED T is represented withinthe digital temperature measurement data DIG T MEAS DATA. The digitalmeasurement data output 114 of the measurement conditioning circuit 104includes the digital temperature measurement output 594 and the digitalmeasurement data DIG MEAS DATA generated by the measurement conditioningcircuit 104 includes the digital temperature measurement data DIG T MEASDATA. The digital measurement data input 118 of the microcontrollercircuit 106 includes the digital temperature measurement input 596. Inone implementation, the analog-to-digital converter circuit 512 includesthe second analog-to-digital converter circuit 582.

The temperature sensor 590 includes positive and negative terminals. Thepositive temperature sense terminal 584 of the temperature measurementconditioning circuit 580 is coupled with the positive terminal and thenegative temperature sense terminal 586 of the temperature measurementconditioning circuit 580 is coupled with the negative terminal. Thetemperature sensor 590 senses a temperature associated with the PVmodule 100 and generates the sensed temperature signal SENSED T based onthe sensed temperature.

FIG. 6 shows a timing diagram 600 of an example of the timing of selectsignals in FIG. 5 in relation to operation of the measurementconditioning circuit 104. The timing diagram 600 reflects a simplifiedscenario for a PV module 100 that is stationary during which the signalsare stable and reflect normal conditions. The measurement conditioningcircuit 104, PV sub-modules 116, current sensor(s) 556, 570, andtemperature sensor 590 generally experience this scenario duringdaylight hours with minor day-to-day and seasonal changes based onactual environmental conditions. In other examples, the amount of lightreceived by the PV sub-modules 116 during daylight hours may vary basedon dust, dirt, debris, snow, ice, rain, clouds, shade, or otherconditions that cause a portion of light that would otherwise reach oneor more of the PV sub-modules 116 to be filtered or blocked. In otherexamples, the PV module 100 tracks the sun or is otherwise adjusted tofollow the sun in relation to a daily cycle. In these examples, theselect signals would be different but react to environmental conditionsin a similar manner to that described herein for the stationary PVsub-module.

A curve 602 shows an example of the second sensed voltage signal SENSEDV2 received by the voltage measurement conditioning circuit 510 from thestring of PV sub-modules 116. The second sensed voltage signal SENSED V2is shown at 67 percent to reflect a condition during daylight hours withfull exposure of the to the PV sub-modules 116 to light. For example,the 67 percent level may represent 40 volts DC. In one implementation,the second sensed voltage signal SENSED V2 varies over daylight hoursdue to numerous factors (e.g., rain, clouds, etc.) and may exhibitcurves and smooths transitions rather than the linear signal shown inFIG. 6. In other examples, the second sensed voltage signal SENSED V2may be lower when the PV sub-modules 116 are not fully exposed to thesun. For example, the second sensed voltage signal SENSED V2 drops tozero (0) percent after sunset until sunrise.

A curve 604 shows an example of the third sensed voltage signal SENSEDV3 received by the voltage measurement conditioning circuit 510 from thestring of PV sub-modules 116. The third sensed voltage signal SENSED V3is shown at 33 percent to reflect a condition during daylight hours withfull exposure of the to the PV sub-modules 116 to light. For example,the 33 percent level may represent 20 volts DC. In one implementation,the third sensed voltage signal SENSED V3 varies over daylight hours dueto numerous factors (e.g., rain, clouds, etc.) and may exhibit curvesand smooths transitions rather than the linear signal shown in FIG. 6.In other examples, the third sensed voltage signal SENSED V3 may belower when the PV sub-modules 116 are not fully exposed to the sun. Forexample, the third sensed voltage signal SENSED V3 drops to zero (0)percent after sunset until sunrise.

A curve 606 shows an example of the sensed current signal SENSED Ireceived by the current measurement conditioning circuit 546 from thecurrent sensor 556. The sensed current signal SENSED I is shown at 50percent to reflect a normal condition during daylight hours with fullexposure of the to the PV sub-modules 116 to light. For example, the 50percent level may represent 7 amps DC. In one implementation, the sensedcurrent signal SENSED I varies over daylight hours due to numerousfactors (e.g., rain, clouds, etc.) and may exhibit curves and smoothstransitions rather than the linear signal shown in FIG. 6. In otherexamples, the sensed current signal SENSED I may be higher duringdegraded or abnormal daylight conditions or lower when the PVsub-modules 116 are not fully exposed to the sun. For example, thesensed current signal SENSED I drops to zero (0) percent after sunsetuntil sunrise.

A curve 608 shows an example of the second sensed current signal SENSEDI2 received by the current measurement conditioning circuit 546 from thesecond current sensor 570. The second sensed current signal SENSED I2 isshown at 50 percent to reflect a normal condition during daylight hourswith full exposure of the to the PV sub-modules 116 to light. Forexample, the 50 percent level may represent 7 amps DC. In oneimplementation, the second sensed current signal SENSED I2 varies overdaylight hours due to numerous factors (e.g., rain, clouds, etc.) andmay exhibit curves and smooths transitions rather than the linear signalshown in FIG. 6. In other examples, the second sensed current signalSENSED I2 may be higher during degraded or abnormal daylight conditionsor lower when the PV sub-modules 116 are not fully exposed to the sun.For example, the second sensed current signal SENSED I2 drops to zero(0) percent after sunset until sunrise. Under normal operation, thesensed current signal SENSED I and second sensed current signal SENSEDI2 are generally the same value within normal tolerances of the sensors556, 570 and other components.

A curve 610 shows an example of the sensed temperature signal SENSED Treceived by the temperature measurement conditioning circuit 580 fromthe temperature sensor 590. The sensed temperature signal SENSED T isshown at 50 percent to reflect a normal condition during daylight hourswith full exposure of the to the PV sub-modules 116 to light. In oneimplementation, the sensed temperature signal SENSED T varies overdaylight hours due to numerous factors (e.g., rain, clouds, etc.) andmay exhibit curves and smooths transitions rather than the linear signalshown in FIG. 6. In other examples, the sensed temperature signal SENSEDT may be higher during degraded or abnormal daylight conditions or lowerwhen the PV sub-modules 116 are not fully exposed to the sun. Forexample, the sensed temperature signal SENSED T may approach ambienttemperature after sunset until sunrise.

FIG. 7 shows another example of the measurement conditioning circuit104. The measurement conditioning circuit 104 includes a voltagemeasurement conditioning circuit 510, a current measurement conditioningcircuit 546, a temperature measurement conditioning circuit 580, amultiplexer circuit 710, and an analog-to-digital converter circuit 712.The voltage measurement conditioning circuit 510 includes the voltagesense terminal 110 of the measurement conditioning circuit 104, a secondvoltage sense terminal 522, a third voltage sense terminal 534, thevoltage reference terminal 112 of the measurement conditioning circuit104, an analog voltage output 514, a second analog voltage output 524,and a third analog voltage output 536. The current measurementconditioning circuit 546 includes first positive and negative currentsense terminals 550, 552, second positive and negative current senseterminals 564, 566, a first analog current output 554, and a secondanalog current output 568. The temperature measurement conditioningcircuit 580 includes positive and negative temperature sense terminals584, 586 and an analog temperature output 588. The multiplexer circuit710 includes an analog voltage input 714 coupled with the analog voltageoutput 514, a second analog voltage input 716 coupled with the secondanalog voltage output 524, a third analog voltage input 718 coupled withthe third analog voltage output 536, a first analog current input 720coupled with the first analog current output 554, a second analogcurrent input 722 coupled with the second analog current output 568, ananalog temperature input 724 coupled with the analog temperature output588, a measurement select input 726 coupled with a measurement selectoutput 728 of the microcontroller circuit 106, and an analog measurementoutput 730. The analog-to-digital converter circuit 712 includes ananalog measurement input 732 coupled with the analog measurement output730 and the digital measurement data output 114 of the measurementconditioning circuit 104 coupled with the digital measurement data input118.

The voltage measurement conditioning circuit 510 receives the sensedvoltage signal SENSED V at the voltage sense terminal 110 from thestring of PV sub-modules 116. The voltage measurement conditioningcircuit 510 receives a second sensed voltage signal SENSED V2 at thesecond voltage sense terminal 522 from the string of PV sub-modules 116.The voltage measurement conditioning circuit 510 receives a third sensedvoltage signal SENSED V3 at the third voltage sense terminal 534 fromthe string of PV sub-modules 116. The voltage measurement conditioningcircuit 510 receives the voltage reference signal at the voltagereference terminal 112 from the string of PV sub-modules 116. Thevoltage measurement conditioning circuit 510 generates an analog voltagesignal ANALOG V at the analog voltage output 514 based on the sensedvoltage signal SENSED V at the voltage sense terminal 110 in referenceto the voltage reference signal at the voltage reference terminal 112.The voltage measurement conditioning circuit 510 generates a secondanalog voltage signal ANALOG V2 at the second analog voltage output 524based on the second sensed voltage signal SENSED V2 at the secondvoltage sense terminal 522 in reference to the voltage reference signalat the voltage reference terminal 112. The voltage measurementconditioning circuit 510 generates a third analog voltage signal ANALOGV3 at the third analog voltage output 536 based on the third sensedvoltage signal SENSED V3 at the third voltage sense terminal 534 inreference to the voltage reference signal at the voltage referenceterminal 112.

The current measurement conditioning circuit 546 receives a first sensedcurrent signal SENSED I at the first positive current sense terminal 550from a first current sensor 556 associated with the string of PVsub-modules 116. The current measurement conditioning circuit 546receives a first current reference signal at the first negative currentsense terminal 552 from the first current sensor 556. The currentmeasurement conditioning circuit 546 receives a second sensed currentsignal SENSED I2 at the second positive current sense terminal 564 froma second current sensor 570 associated with the string of PV sub-modules116. The current measurement conditioning circuit 546 receives a secondcurrent reference signal at the second negative current sense terminal566 from the second current sensor 570. The current measurementconditioning circuit 546 generates a first analog current signal ANALOGI at the first analog current output 554 based on the first sensedcurrent signal SENSED I at the first positive current sense terminal 550in reference to the first current reference signal at the first negativecurrent sense terminal 552. The current measurement conditioning circuit546 generates a second analog current signal ANALOG I2 at the secondanalog current output 568 based on the second sensed current signalSENSED I2 at the second positive current sense terminal 564 in referenceto the second current reference signal at the second negative currentsense terminal 566.

The temperature measurement conditioning circuit 580 receives a sensedtemperature signal SENSED T at the positive temperature sense terminal584 from a temperature sensor 590 associated with the string of PVsub-modules 116. The temperature measurement conditioning circuit 580receives a temperature reference signal at the negative temperaturesense terminal 586 from the temperature sensor 590. The temperaturemeasurement conditioning circuit 580 generates an analog temperaturesignal ANALOG T at the analog temperature output 588 based on the sensedtemperature signal SENSED T at the positive temperature sense terminal584 in reference to the temperature reference signal at the negativetemperature sense terminal 586.

The microcontroller circuit 106 generates a measurement select signalMEAS SELECT at the measurement select output 728 to enable selection ofa select analog signal from multiple analog signals at multiple analoginputs to the multiplexer circuit 710 for routing the select analogsignal to the analog measurement output 730. The multiplexer circuit 710routes the analog voltage input 714, the second analog voltage input716, the third analog voltage input 718, the first analog current input720, the second analog current input 722, or the analog temperatureinput 724 to the analog measurement output 730 in response to themeasurement select signal MEAS SELECT at the measurement select input726 to provide an analog measurement signal ANALOG MEAS to the analogmeasurement output 730. The analog-to-digital converter circuit 712generates the digital measurement data DIG MEAS DATA at the digitalmeasurement data output 114 based on the analog measurement signalANALOG MEAS at the analog measurement input 732.

In another example, the string of PV sub-modules 116 includes first,second, and third PV sub-modules 1702, 1704, 1706 (FIG. 17). The firstPV sub-module 1702 includes a positive DC power terminal 1714, thesecond PV sub-module 1704 includes a positive DC power terminal 1722,and the third PV sub-module 1706 includes a positive DC power terminal1728 and a negative DC power terminal 1730. The voltage measurementconditioning circuit 510 receives the sensed voltage signal SENSED Vfrom the positive DC power terminal 1714 of the first PV sub-module 1702via the voltage sense terminal 110. The voltage measurement conditioningcircuit 510 receives the second sensed voltage signal SENSED V2 from thepositive DC power terminal 1722 of the second PV sub-module 1704 via thesecond voltage sense terminal 522. The voltage measurement conditioningcircuit 510 receives the third sensed voltage signal SENSED V3 from thepositive DC power terminal 1728 of the third PV sub-module via the thirdvoltage sense terminal 534. The voltage measurement conditioning circuit510 receives the voltage reference signal from the negative DC powerterminal 1730 of the third PV sub-module 1706 via the voltage referenceterminal 112.

In another example, the microcontroller circuit 106 generates powermeasurement data associated with the string of PV sub-modules 116 basedon the digital measurement data DIG MEAS DATA associated with the sensedvoltage signal SENSED V and the digital measurement data DIG MEAS DATAassociated with the first sensed current signal SENSED I or the secondsensed current signal SENSED I2. The measurement data stream MEAS DATASTREAM is also based on the power measurement data such that the powermeasurement data is represented within the measurement data stream MEASDATA STREAM and the output communication signal COMM SIG OUT.

In another example, the string of PV sub-modules 116 includes a positiveDC power terminal 1714 (FIG. 17) coupled with a positive DC power line1718 of a DC bus 1720 and a negative DC power terminal 1730 coupled witha negative DC power line 1732 of the DC bus 1720. In one implementation,the first current sensor 556 includes positive and negative terminals.The first positive current sense terminal 550 of the current measurementconditioning circuit 546 is coupled with the positive terminal and thefirst negative current sense terminal 552 of the current measurementconditioning circuit 546 is coupled with the negative terminal. Thefirst current sensor 556 senses current passing through the positive DCpower line 1718 between the DC bus 1720 and the positive DC powerterminal 1714 of the string of PV sub-modules 116. The first currentsensor 556 generates the first sensed current signal SENSED I based onthe sensed current. In another implementation, the second current sensor570 includes positive and negative terminals. The second positivecurrent sense terminal 564 of the current measurement conditioningcircuit 546 is coupled with the positive terminal and the secondnegative current sense terminal 566 of the current measurementconditioning circuit 546 is coupled with the negative terminal. Thesecond current sensor 570 senses current passing through the negative DCpower line 1732 between the negative DC power terminal 1730 of thestring of PV sub-modules 116 and the DC bus 1720. The second currentsensor 570 generates the second sensed current signal SENSED I2 based onthe sensed current.

In another example, the temperature sensor 590 includes positive andnegative terminals. The positive temperature sense terminal 584 of thetemperature measurement conditioning circuit 580 is coupled with thepositive terminal and the negative temperature sense terminal 586 of thetemperature measurement conditioning circuit 580 is coupled with thenegative terminal. The temperature sensor 590 senses a temperatureassociated with the PV module 100 and generates the sensed temperaturesignal SENSED T based on the sensed temperature.

FIG. 8 shows an example of the transmitter circuit 108. The transmittercircuit 108 includes a crystal oscillator circuit 810, adigital-to-analog converter circuit 812, a modulator circuit 814, and apower amplifier circuit 816. The crystal oscillator circuit 810 includesthe modulation clock output 128 of the transmitter circuit 108 coupledwith the modulation clock input 120 of the microcontroller circuit 106.The digital-to-analog converter circuit 812 includes the measurementdata stream input 126 of the transmitter circuit 108 coupled with themeasurement data stream output 122, a second modulation clock input 818coupled with the modulation clock output 128, and an analog measurementoutput 820. The modulator circuit 814 includes an analog measurementinput 822 coupled with the analog measurement output 820, a modulationclock input 824 coupled with the modulation clock output 128, and amodulated measurement output 826. The power amplifier circuit 816includes a third modulated measurement input 828 coupled with themodulated measurement output 826, the transmit select input 130 of thetransmitter circuit 108 coupled with the transmit select output 124, andthe positive and negative output communication terminals 132, 134 of thetransmitter circuit 108. The crystal oscillator circuit 810 generatesthe modulation clock signal MOD CLK at the modulation clock output 128.The digital-to-analog converter circuit 812 generates an analogmeasurement signal ANALOG MEAS at the analog measurement output 820based on the measurement data stream MEAS DATA STREAM at the measurementdata stream input 126 in response to the modulation clock signal MOD CLKat the second modulation clock input 818. The modulator circuit 814generates a modulated measurement signal MOD MEAS at the modulatedmeasurement output 826 based on the analog measurement signal ANALOGMEAS at the analog measurement input 822 in response to the modulationclock signal MOD CLK at the modulation clock input 824. The poweramplifier circuit 816 generates the output communication signal COMM SIGOUT based on the modulated measurement signal MOD MEAS at the thirdmodulated measurement input 828. The power amplifier circuit 816transmits the output communication signal COMM SIG OUT to thecommunication interface circuit 136 via the positive and negative outputcommunication terminals 132, 134 in response to the transmit selectsignal XMIT SELECT at the transmit select input 130.

In another example, the communication interface circuit 136 includes apositive DC power terminal 1802 (e.g., FIG. 18) coupled with a positiveDC power line 1718 (FIG. 17) of a DC bus 1720 and a negative DC powerterminal 1804. The string of PV sub-modules 116 includes a positive DCpower line 1718 coupled with the negative DC power terminal 1804 of thecommunication interface circuit 136 and a negative DC power terminal1730 coupled with a negative DC power line 1732 of the DC bus 1720. Themeasurement data stream MEAS DATA STREAM, analog measurement signalANALOG MEAS, and modulated measurement signal MOD MEAS are formed suchthat the output communication signal COMM SIG OUT is a power linecommunication signal. The communication interface circuit 136 istransmits the PLC signal to a remote receiver circuit 1806 via thepositive and negative DC power lines 1718, 1732 of the DC bus 1720 byapplying the output communication signal COMM SIG OUT received from thepower amplifier circuit 816 to the positive and negative DC powerterminals 1802, 1804 of the communication interface circuit 136. In oneimplementation, the PLC signal is a spread frequency shift keyingwaveform. In one example, the S-FSK waveform is compliant with PLCprotocol requirements of SunSpec Interoperability Specification,Communication Signal for Rapid Shutdown, Version 34. The microcontrollercircuit 106 and the power amplifier circuit 816 transmit the outputcommunication signal COMM SIG OUT during a zero energy period of arepetitive data frame specified in the PLC protocol requirements of theSunSpec Interoperability Specification.

In another example, the communication interface circuit 136 includes anantenna 1902 (e.g., FIG. 19). The communication interface circuit 136generates a wireless communication signal based on the outputcommunication signal COMM SIG OUT received from the power amplifiercircuit 816. The communication interface circuit 136 transmits thewireless communication signal to a remote receiver circuit 1904 via theantenna 1902. In another example, the communication interface circuit136 generates a wired control line communication signal based on theoutput communication signal COMM SIG OUT received from the poweramplifier circuit 816. The communication interface circuit 136 transmitsthe wired control line communication signal to a remotereceiver/transmitter circuit 2006 (e.g., FIG. 20) via wired transmissionlines coupling the communication interface circuit 136 to the remotereceiver/transmitter circuit 2006.

In another example, the digital-to-analog converter circuit 812 uses themodulation clock signal MOD CLK to sample the measurement data streamMEAS DATA STREAM at the measurement data stream input 126 to form theanalog measurement signal ANALOG MEAS at the analog measurement output820. In another example, the modulator circuit 814 uses the modulationclock signal MOD CLK to sample the analog measurement signal ANALOG MEASat the analog measurement input 822 to form the modulated measurementsignal MOD MEAS at the modulated measurement output 826.

FIG. 9 shows an example of a method 900 for monitoring a PV module 100(e.g., FIG. 1). In several examples, the monitoring circuit 102described in FIGS. 1-8 implements the method 900. In FIG. 9, the method900 begins at 902 with receiving a sensed voltage signal SENSED V at avoltage sense terminal 110 of a measurement conditioning circuit 104from a string of PV sub-modules 116 associated with the PV module 100.At 904, a voltage reference signal is received at a voltage referenceterminal 112 of the measurement conditioning circuit 104 from the stringof PV sub-modules 116. At 906, the method 900 also includes generatingdigital measurement data DIG MEAS DATA at a digital measurement dataoutput 114 of the measurement conditioning circuit 104 based on thesensed voltage signal SENSED V in reference to the voltage referencesignal such that the sensed voltage signal SENSED V is representedwithin the digital measurement data DIG MEAS DATA. At 908, a modulationclock signal MOD CLK is generated at a modulation clock output 128 of atransmitter circuit 108. At 910, the method 900 also includes generatinga measurement data stream MEAS DATA STREAM at a measurement data streamoutput 122 of a microcontroller circuit 106 based on the digitalmeasurement data DIG MEAS DATA at a digital measurement data input 118and the modulation clock signal MOD CLK at a modulation clock input 120such that the sensed voltage signal SENSED V is represented within themeasurement data stream MEAS DATA STREAM. At 912, an outputcommunication signal COMM SIG OUT is generated at the transmittercircuit 108 based on the modulation clock signal MOD CLK and themeasurement data stream MEAS DATA STREAM at a measurement data streaminput 126 such that the sensed voltage signal SENSED V is representedwithin the output communication signal COMM SIG OUT. At 914, the method900 also includes generating a transmit select signal XMIT SELECT at atransmit select output 124 of the microcontroller circuit 106 based onthe measurement data stream MEAS DATA STREAM. At 916, the outputcommunication signal COMM SIG OUT is transmitted from the transmittercircuit 108 to a communication interface circuit 136 via positive andnegative output communication terminals 132, 134 in response to thetransmit select signal XMIT SELECT at a transmit select input 130 of thetransmitter circuit 108. In one implementation, the string of PVsub-modules 116 includes first and second PV sub-modules 1702, 1704/1706(FIG. 17).

In another example, the first PV sub-module 1702 (FIG. 17) includes apositive DC power terminal 1714 and the second PV sub-module 1704/1706includes a negative DC power terminal 1724/1730. In this example, themethod 900 also includes receiving the sensed voltage signal SENSED Vfrom the positive DC power terminal 1714 of the first PV sub-module 1702via the voltage sense terminal 110. The method 900 also includesreceiving the voltage reference signal from the negative DC powerterminal 1724/1730 of the second PV sub-module 1704/1706 via the voltagereference terminal 112.

In another example, the measurement data stream MEAS DATA STREAMincludes a first representation of the digital measurement data DIG MEASDATA in data burst form for a first frequency of a spread frequencyshift keying modulation scheme and a second representation of thedigital measurement data DIG MEAS DATA in data burst form for a secondfrequency of the S-FSK modulation scheme. In another example, the outputcommunication signal COMM SIG OUT carries modulated data representativeof the first and second representations of the digital measurement dataDIG MEAS DATA using the first and second frequencies of the S-FSKmodulation scheme. In one implementation, the output communicationsignal COMM SIG OUT is compliant with PLC protocol requirements ofSunSpec Interoperability Specification, Communication Signal for RapidShutdown, Version 34. In this implementation, the method 900 alsoincludes transmitting the output communication signal COMM SIG OUTcarrying modulated data representative of the digital measurement dataDIG MEAS DATA from the transmitter circuit 108 (e.g., FIG. 1) via thepositive and negative output communication terminals 132, 134 during azero energy period of a repetitive data frame specified in the PLCprotocol requirements of the SunSpec Interoperability Specification.

In another example, the method 900 also includes using the modulationclock signal MOD CLK at the microcontroller circuit 106 (e.g., FIG. 1)to sample the digital measurement data DIG MEAS DATA to form themeasurement data stream MEAS DATA STREAM. In another example, the method900 also includes using the modulation clock signal MOD CLK at thetransmitter circuit 108 to sample the measurement data stream MEAS DATASTREAM to form the output communication signal COMM SIG OUT.

FIGS. 9 and 10 show another example of the method 900 which alsoincludes 1002 where an input communication signal COMM SIG IN isreceived at positive and negative input communication terminals 144, 146(FIG. 1) of a receiver circuit 142 from the communication interfacecircuit 136. At 1004, a demodulation clock signal DEMOD CLK is generatedat a demodulation clock output 150 of the receiver circuit 142. At 1006,the method 900 also includes generating an input communication datastream INPUT COMM DATA STREAM at an input communication data streamoutput 148 of the receiver circuit 142 based on the input communicationsignal COMM SIG IN at the positive and negative input communicationterminals 144, 146 and the demodulation clock signal DEMOD CLK. At 1008,the input communication data stream INPUT COMM DATA STREAM is receivedfrom the receiver circuit 142 at an input communication data streaminput 138 of the microcontroller circuit 106. At 1010, the method 900also includes receiving the demodulation clock signal DEMOD CLK from thereceiver circuit 142 at a demodulation clock input 140 of themicrocontroller circuit 106. At 1012, the input communication datastream INPUT COMM DATA STREAM is processed at the microcontrollercircuit 106 using the demodulation clock signal DEMOD CLK to detectmodulated data carried by the input communication signal COMM SIG IN andrepresented within the input communication data stream INPUT COMM DATASTREAM. At 1014, the method 900 also includes generating the transmitselect signal XMIT SELECT at the microcontroller circuit 106 in responseto detecting, for a predetermined time, an absence of the modulated datain the input communication data stream INPUT COMM DATA STREAMrepresenting the input communication signal COMM SIG IN.

In another example, the input communication signal COMM SIG IN is basedon a power line communication signal associated with the PV module 100(e.g., FIG. 1). In one implementation, the method 900 also includesreceiving the PLC signal at the communication interface circuit 136 froma remote transmitter circuit 1806 (FIG. 18) via a DC bus 1720 associatedwith the PV module 100. The input communication signal COMM SIG IN isbased on data carried by the PLC signal transmitted via the DC bus 1720.

In another example, the input communication signal COMM SIG IN is basedon a wireless communication signal associated with the PV module 100(FIG. 1). In one implementation, the method 900 also includes receivingthe wireless communication signal at the communication interface circuit136 from a remote transmitter circuit 1904 (FIG. 19). The inputcommunication signal COMM SIG IN is based on data carried by thewireless communication signal.

In another example, the input communication signal COMM SIG IN is basedon a wired control line communication signal associated with the PVmodule 100 (FIG. 1). In one implementation, the method 900 also includesreceiving the wired control line communication signal at thecommunication interface circuit 136 from a remote receiver/transmittercircuit 2006 (e.g., FIG. 20) via a wired control line. The inputcommunication signal COMM SIG IN is based on data carried by the wiredcontrol line communication signal.

In another example, the method 900 also includes using the demodulationclock signal DEMOD CLK at the receiver circuit 142 (FIG. 1) to samplethe input communication signal COMM SIG IN to form the inputcommunication data stream INPUT COMM DATA STREAM. In another example,the method 900 also includes using the demodulation clock signal DEMODCLK at the microcontroller circuit 106 to demodulate data carried by theinput communication data stream INPUT COMM DATA STREAM.

FIGS. 9-11 show another example of the method 900 which also includes1102 where a PTO signal PTO is generated at a PTO output 152 (FIG. 1) ofthe microcontroller circuit 106 in response to detecting a presence ofmodulated data carried by the input communication signal COMM SIG IN andrepresented within the input communication data stream INPUT COMM DATASTREAM that is representative of a keep alive command associated withthe PV module 100. At 1104, a local PTO signal LOCAL PTO is generated ata local PTO output terminal 158 of a PTO distribution circuit 154 basedon the PTO signal PTO at a PTO input 156. At 1106, the method 900 alsoincludes generating a remote PTO signal REMOTE PTO at a remote PTOoutput terminal 160 of a PTO distribution circuit 154 based on the PTOsignal PTO. In one implementation, the string of PV modules includes aPV sub-module 1702 (e.g., FIG. 17). In this implementation, the method900 also includes providing the local PTO signal LOCAL PTO from the PTOdistribution circuit 154 to a sub-module controller circuit 162associated with the PV sub-module 1702. In another implementation, themethod 900 also includes providing the remote PTO signal REMOTE PTO fromthe PTO distribution circuit 154 to a shutdown initiation device 164associated with the PV module 100.

FIGS. 9-12 show an example of the method 900 in which the PTOdistribution circuit 154 (FIG. 1) includes a local PTO amplifier circuit310 (e.g., FIG. 3) and a remote PTO amplifier circuit 312. In thisexample, at 1202, the method 900 also includes generating the local PTOsignal LOCAL PTO at a local PTO output terminal 158 of the local PTOamplifier circuit 310 based on the PTO signal PTO at a first PTO input314. At 1204; the remote PTO signal REMOTE PTO is generated at a remotePTO output terminal 160 of the remote PTO amplifier circuit 312 based onthe PTO signal PTO at a second PTO input 316. The PTO input 156 of thePTO distribution circuit 154 includes the first and second PTO inputs314, 316, the local PTO output terminal 158 of the PTO distributioncircuit 154 includes the local PTO output terminal 158 of the local PTOamplifier circuit 310, and the remote PTO output terminal 160 of the PTOdistribution circuit 154 includes the remote PTO output terminal 160 ofthe remote PTO amplifier circuit 312.

FIGS. 9, 10, and 13 show an example of the method 900 in which thereceiver circuit 142 (FIG. 1) includes a bandpass filter circuit 410(e.g., FIG. 4), a crystal oscillator circuit 412, and ananalog-to-digital converter circuit 414. In this example, at 1302, themethod 900 also includes generating a filtered input waveform FILTEREDINPUT WAVEFORM at a filtered input communication output 416 of thebandpass filter circuit 410 based on the input communication signal COMMSIG IN at positive and negative input communication terminals 144, 146.At 1304, the demodulation clock signal DEMOD CLK is generated at ademodulation clock output 150 of the crystal oscillator circuit 412. At1306, the method 900 also includes generating the input communicationdata stream INPUT COMM DATA STREAM at an input communication data streamoutput 148 of the analog-to-digital converter circuit 414 based on thefiltered input waveform FILTERED INPUT WAVEFORM at a filtered inputcommunication input 418 in response to the demodulation clock signalDEMOD CLK at a second demodulation clock input 420. The positive andnegative input communication terminals 144, 146 of the receiver circuit142 include the positive and negative input communication terminals 144,146 of the bandpass filter circuit 410. The demodulation clock output150 of the receiver circuit 142 includes the demodulation clock output150 of the crystal oscillator circuit 412. The input communication datastream output 148 of the receiver circuit 142 includes the inputcommunication data stream output 148 of the analog-to-digital convertercircuit 414. In another example, the method 900 also includes using thedemodulation clock signal DEMOD CLK at the analog-to-digital convertercircuit 414 to sample the filtered input waveform FILTERED INPUTWAVEFORM to form the input communication data stream INPUT COMM DATASTREAM. In another example, the method 900 also includes receiving theinput communication signal COMM SIG IN from the communication interfacecircuit 136 at the bandpass filter circuit 410.

FIGS. 9 and 14 show an example of the method 900 in which themeasurement conditioning circuit 104 (e.g., FIG. 1) includes a voltagemeasurement conditioning circuit 510 (e.g., FIG. 5) and ananalog-to-digital converter circuit 512. In this example, at 1402, themethod 900 also includes receiving the sensed voltage signal SENSED V ata voltage sense terminal 110 of the voltage measurement conditioningcircuit 510 from the string of PV sub-modules 116. At 1404, the voltagereference signal is received at a voltage reference terminal 112 of thevoltage measurement conditioning circuit 510 from the string of PVsub-modules 116. At 1406, the method 900 also includes generating ananalog voltage signal ANALOG V at an analog voltage output 514 of thevoltage measurement conditioning circuit 510 based on the sensed voltagesignal SENSED V at the voltage sense terminal 110 in reference to thevoltage reference signal at the voltage reference terminal 112. At 1408,digital voltage measurement data DIG V MEAS DATA is generated at adigital voltage measurement output 518 of the analog-to-digitalconverter circuit 512 based on the analog voltage signal ANALOG V at ananalog voltage input 516 such that the sensed voltage signal SENSED V isrepresented within the digital voltage measurement data DIG V MEAS DATA.The digital measurement data output 114 of the measurement conditioningcircuit 104 includes the digital voltage measurement output 518 and thedigital measurement data DIG MEAS DATA generated by the measurementconditioning circuit 104 includes the digital voltage measurement dataDIG V MEAS DATA. The digital measurement data input 118 of themicrocontroller circuit 106 includes a digital voltage measurement input520 coupled with the digital voltage measurement output 518.

In another example, the string of PV sub-modules 116 (e.g., FIG. 1)includes first and second PV sub-modules 1702, 1704/1706 (e.g., FIG.17). In this example, the method 900 also includes receiving the sensedvoltage signal SENSED V at the voltage sense terminal 110 of the voltagemeasurement conditioning circuit 510 from a positive DC power terminal1714 of the first PV sub-module 1702. The method 900 also includesreceiving the voltage reference signal at the voltage reference terminal112 of the voltage measurement conditioning circuit 510 from a negativeDC power terminal 1724/1730 of the second PV sub-module 1704/1706.

In another example, the measurement conditioning circuit 104 (e.g.,FIG. 1) also includes a second analog-to-digital converter circuit 526(e.g., FIG. 5). In this example, the method 900 also includes receivinga second sensed voltage signal SENSED V2 at a second voltage senseterminal 522 of the voltage measurement conditioning circuit 510 fromthe string of PV sub-modules 116. The method 900 also includesgenerating a second analog voltage signal ANALOG V2 at a second analogvoltage output 524 of the voltage measurement conditioning circuit 510based on the second sensed voltage signal SENSED V2 at the secondvoltage sense terminal 522 in reference to the voltage reference signalat the voltage reference terminal 112. The method 900 also includesgenerating second digital voltage measurement data DIG V2 MEAS DATA at asecond digital voltage measurement output 530 of the secondanalog-to-digital converter circuit 526 based on the second analogvoltage signal ANALOG V2 at a second analog voltage input 528 such thatthe second sensed voltage signal SENSED V2 is represented within thesecond digital voltage measurement data DIG V2 MEAS DATA. The digitalmeasurement data output 114 of the measurement conditioning circuit 104includes the second digital voltage measurement output 530 and thedigital measurement data DIG MEAS DATA generated by the measurementconditioning circuit 104 includes the second digital voltage measurementdata DIG V2 MEAS DATA. The digital measurement data input 118 of themicrocontroller circuit 106 includes a second digital voltagemeasurement input 532 coupled with the second digital voltagemeasurement output 530.

In another example, the string of PV sub-modules 116 (e.g., FIG. 1)includes first and second PV sub-modules 1702, 1704/1706 (e.g., FIG.17). In this example, the method 900 also includes receiving the sensedvoltage signal SENSED V at the voltage sense terminal 110 of the voltagemeasurement conditioning circuit 510 (e.g., FIG. 5) from a positive DCpower terminal 1714 of the first PV sub-module 1702. The method 900 alsoincludes receiving the second sensed voltage signal SENSED V2 at thesecond voltage sense terminal 522 of the voltage measurementconditioning circuit 510 from a positive DC power terminal 1722/1728 ofthe second PV sub-module 1704/1706. The method 900 also includesreceiving the voltage reference signal at the voltage reference terminal112 of the voltage measurement conditioning circuit 510 from a negativeDC power terminal 1724/1730 of the second PV sub-module 1704/1706.

In another example, the measurement conditioning circuit 104 (e.g.,FIG. 1) also includes a third analog-to-digital converter circuit 538(e.g., FIG. 5). In this example, the method 900 also includes receivinga third sensed voltage signal SENSED V3 at a third voltage senseterminal 534 of the voltage measurement conditioning circuit 510 fromthe string of PV sub-modules 116. The method 900 also includesgenerating a third analog voltage signal ANALOG V3 at a third analogvoltage output 536 of the voltage measurement conditioning circuit 510based on the third sensed voltage signal SENSED V3 at the third voltagesense terminal 534 in reference to the voltage reference signal at thevoltage reference terminal 112. The method 900 also includes generatingthird digital voltage measurement data DIG V3 MEAS DATA at a thirddigital voltage measurement output 542 of the third analog-to-digitalconverter circuit 538 based on the third analog voltage signal ANALOG V3at a third analog voltage input 540 such that the third sensed voltagesignal SENSED V3 is represented within the third digital voltagemeasurement data DIG V3 MEAS DATA. The digital measurement data output114 of the measurement conditioning circuit 104 includes the thirddigital voltage measurement output 542 and the digital measurement dataDIG MEAS DATA generated by the measurement conditioning circuit 104includes the third digital voltage measurement data DIG V3 MEAS DATA.The digital measurement data input 118 of the microcontroller circuit106 includes a third digital voltage measurement input 544 coupled withthe third digital voltage measurement output 542.

In another example, the string of PV sub-modules 116 (e.g., FIG. 1)includes first, second, and third PV sub-modules 1702, 1704, 1706 (e.g.,FIG. 17). In this example, the method 900 also includes receiving thesensed voltage signal SENSED V at the voltage sense terminal 110 of thevoltage measurement conditioning circuit 510 from a positive DC powerterminal 1714 of the first PV sub-module 1702. The method 900 alsoincludes receiving the second sensed voltage signal SENSED V2 at thesecond voltage sense terminal 522 of the voltage measurementconditioning circuit 510 from a positive DC power terminal 1722 of thesecond PV sub-module 1704. The method 900 also includes receiving thethird sensed voltage signal SENSED V3 at the third voltage senseterminal 534 of the voltage measurement conditioning circuit 510 from apositive DC power terminal 1728 of the third PV sub-module 1706. Themethod 900 also includes receiving the voltage reference signal at thevoltage reference terminal 112 of the voltage measurement conditioningcircuit 510 from a negative DC power terminal 1730 of the third PVsub-module 1706.

In another example, the measurement conditioning circuit 104 (e.g.,FIG. 1) also includes a current measurement conditioning circuit 546(e.g., FIG. 5) and a second analog-to-digital converter circuit 548. Inthis example, the method 900 also includes receiving a sensed currentsignal SENSED I at a positive current sense terminal 550 of the currentmeasurement conditioning circuit 546 from a current sensor 556associated with the string of PV sub-modules 116. The method 900 alsoincludes receiving a current reference signal at a negative currentsense terminal 552 of the current measurement conditioning circuit 546from the current sensor 556. The method 900 also includes generating ananalog current signal ANALOG I at an analog current output 554 of thecurrent measurement conditioning circuit 546 based on the sensed currentsignal SENSED I at the positive current sense terminal 550 in referenceto the current reference signal at the negative current sense terminal552. The method 900 also includes generating digital current measurementdata DIG I MEAS DATA at a digital current measurement output 560 of thesecond analog-to-digital converter circuit 548 based on the analogcurrent signal ANALOG I at an analog current input 558 such that thesensed current signal SENSED I is represented within the digital currentmeasurement data DIG I MEAS DATA. The digital measurement data output114 of the measurement conditioning circuit 104 includes the digitalcurrent measurement output 560 and the digital measurement data DIG MEASDATA generated by the measurement conditioning circuit 104 includes thedigital current measurement data DIG I MEAS DATA. The digitalmeasurement data input 118 of the microcontroller circuit 106 includes adigital current measurement input 562 coupled with the digital currentmeasurement output 560.

In another example, the string of PV sub-modules 116 (e.g., FIG. 1)includes a positive DC power terminal 1714 (e.g., FIG. 17) coupled witha positive DC power line 1718 of a DC bus 1720 and a negative DC powerterminal 1730 coupled with a negative DC power line 1732 of the DC bus1720. In this example, the method 900 also includes sensing currentpassing through the string of PV sub-modules 116 between the positive DCpower line 1718 and the negative DC power line 1732 at the currentsensor 556. The method 900 also includes generating the sensed currentsignal SENSED I at the current sensor 556 based on the sensed current.The current sensor 556 includes positive and negative terminals. Thepositive current sense terminal 550 of the current measurementconditioning circuit 546 is coupled with the positive terminal and thenegative current sense terminal 552 of the current measurementconditioning circuit 546 is coupled with the negative terminal. In oneimplementation, the method 900 also includes sensing current passingthrough the positive DC power line 1718 between the DC bus 1720 and thepositive DC power terminal 1714 of the string of PV sub-modules 116 atthe current sensor 556. In another implementation, the method 900 alsoincludes sensing current passing through the negative DC power line 1732between the negative DC power terminal 1730 of the string of PVsub-modules 116 and the DC bus 1720 at the current sensor 556.

In another example, the method 900 also includes generating powermeasurement data associated with the string of PV sub-modules 116 (e.g.,FIG. 1) at the microcontroller circuit 106 based on the digital voltagemeasurement data DIG V MEAS DATA associated with the sensed voltagesignal SENSED V and the digital current measurement data DIG I MEAS DATAassociated with the sensed current signal SENSED I. The measurement datastream MEAS DATA STREAM is also based on the power measurement data suchthat the power measurement data is represented within the measurementdata stream MEAS DATA STREAM and the output communication signal COMMSIG OUT.

In another example, the measurement conditioning circuit 104 (e.g.,FIG. 1) also includes a third analog-to-digital converter circuit 572(e.g., FIG. 5). In this example, the method 900 also includes receivinga second sensed current signal SENSED I2 at a second positive currentsense terminal 564 of the current measurement conditioning circuit 546from a second current sensor 570 associated with the string of PVsub-modules 116. The method 900 also includes receiving a second currentreference signal at a second negative current sense terminal 566 of thecurrent measurement conditioning circuit 546 from the second currentsensor 570. The method 900 also includes generating a second analogcurrent signal ANALOG I2 at a second analog current output 568 of thecurrent measurement conditioning circuit 546 based on the second sensedcurrent signal SENSED I2 at the second positive current sense terminal564 in reference to the second current reference signal at the secondnegative current sense terminal 566. The method 900 also includesgenerating second digital current measurement data DIG I2 MEAS DATA at asecond digital current measurement output 576 of the thirdanalog-to-digital converter circuit 572 based on the second analogcurrent signal ANALOG I2 at a second analog current input 574 such thatthe second sensed current signal SENSED I2 is represented within thesecond digital current measurement data DIG I2 MEAS DATA. The digitalmeasurement data output 114 of the measurement conditioning circuit 104includes the second digital current measurement output 576 and thedigital measurement data DIG MEAS DATA generated by the measurementconditioning circuit 104 includes the second digital current measurementdata DIG I2 MEAS DATA. The digital measurement data input 118 of themicrocontroller circuit 106 includes a second digital currentmeasurement input 578 coupled with the second digital currentmeasurement output 576.

In another example, the string of PV sub-modules 116 (e.g., FIG. 1)includes a positive DC power terminal 1714 (e.g., FIG. 17) coupled witha positive DC power line 1718 of a DC bus 1720 and a negative DC powerterminal 1730 coupled with a negative DC power line 1732 of the DC bus1720. In another example, the current sensor 556 (e.g., FIG. 5) includespositive and negative terminals. The positive current sense terminal 550of the current measurement conditioning circuit 546 is coupled with thepositive terminal and the negative current sense terminal 552 of thecurrent measurement conditioning circuit 546 is coupled with thenegative terminal. In this example, the method 900 also includes sensingcurrent passing through the positive DC power line 1718 between the DCbus 1720 and the positive DC power terminal 1714 of the string of PVsub-modules 116 at the current sensor 556. The method 900 also includesgenerating the sensed current signal SENSED I at the current sensor 556based on the sensed current. In another example, the second currentsensor 570 includes second positive and negative terminals. The secondpositive current sense terminal 564 of the current measurementconditioning circuit 546 is coupled with the second positive terminaland the second negative current sense terminal 566 of the currentmeasurement conditioning circuit 546 is coupled with the second negativeterminal. In this example, the method 900 also includes sensing currentpassing through the negative DC power line 1732 between the negative DCpower terminal 1730 of the string of PV sub-modules 116 and the DC bus1720 at the second current sensor 570. The method 900 also includesgenerating the second sensed current signal SENSED I2 at the secondcurrent sensor 570 based on the sensed current.

In another example, the measurement conditioning circuit 104 (e.g.,FIG. 1) also includes a temperature measurement conditioning circuit 580(e.g., FIG. 5) and a second analog-to-digital converter circuit 582. Inthis example, the method 900 also includes receiving a sensedtemperature signal SENSED T at a positive temperature sense terminal 584of the temperature measurement conditioning circuit 580 from atemperature sensor 590 associated with the string of PV sub-modules 116.The method 900 also includes receiving a temperature reference signal ata negative temperature sense terminal 586 of the temperature measurementconditioning circuit 580 from the temperature sensor 590. The method 900also includes generating an analog temperature signal ANALOG T at ananalog temperature output 588 of the temperature measurementconditioning circuit 580 based on the sensed temperature signal SENSED Tat the positive temperature sense terminal 584 in reference to thetemperature reference signal at the negative temperature sense terminal586. The method 900 also includes generating digital temperaturemeasurement data DIG T MEAS DATA at a digital temperature measurementoutput 594 of the second analog-to-digital converter circuit 582 basedon the analog temperature signal ANALOG T at an analog temperature input592 such that the sensed temperature signal SENSED T is representedwithin the digital temperature measurement data DIG T MEAS DATA. Thedigital measurement data output 114 of the measurement conditioningcircuit 104 includes the digital temperature measurement output 594 andthe digital measurement data DIG MEAS DATA generated by the measurementconditioning circuit 104 includes the digital temperature measurementdata DIG T MEAS DATA. The digital measurement data input 118 of themicrocontroller circuit 106 includes a digital temperature measurementinput 596 coupled with the digital temperature measurement output 594.

In another example, the method 900 also includes sensing a temperatureassociated with the PV module 100 (e.g., FIG. 1) at the temperaturesensor 590 (e.g., FIG. 5). The method 900 also includes generating thesensed temperature signal SENSED T at the temperature sensor 590 basedon the sensed temperature. The temperature sensor 590 includes positiveand negative terminals. The positive temperature sense terminal 584 ofthe temperature measurement conditioning circuit 580 is coupled with thepositive terminal and the negative temperature sense terminal 586 of thetemperature measurement conditioning circuit 580 is coupled with thenegative terminal.

FIGS. 9 and 15 show another example of the method 900 in whichmeasurement conditioning circuit 104 (e.g., FIG. 1) includes a voltagemeasurement conditioning circuit 510 (e.g., FIG. 5), a currentmeasurement conditioning circuit 546, a temperature measurementconditioning circuit 580, a multiplexer circuit 710 (e.g., FIG. 7), andan analog-to-digital converter circuit 712. In this example, at 1502,the method 900 also includes receiving the sensed voltage signal SENSEDV at a voltage sense terminal 110 of the voltage measurementconditioning circuit 510 from the string of PV sub-modules 116. At 1504;a second sensed voltage signal SENSED V2 is received at a second voltagesense terminal 522 of the voltage measurement conditioning circuit 510from the string of PV sub-modules 116. At 1506, the method 900 alsoincludes receiving a third sensed voltage signal SENSED V3 at a thirdvoltage sense terminal 534 of the voltage measurement conditioningcircuit 510 from the string of PV sub-modules 116. At 1508, the voltagereference signal is received at a voltage reference terminal 112 of thevoltage measurement conditioning circuit 510 from the string of PVsub-modules 116. At 1510, the method 900 also includes generating ananalog voltage signal ANALOG V at an analog voltage output 514 of thevoltage measurement conditioning circuit 510 based on the sensed voltagesignal SENSED V at the voltage sense terminal 110 in reference to thevoltage reference signal at the voltage reference terminal 112. At 1512,a second analog voltage signal ANALOG V2 is generated at a second analogvoltage output 524 of the voltage measurement conditioning circuit 510based on the second sensed voltage signal SENSED V2 at the secondvoltage sense terminal 522 in reference to the voltage reference signalat the voltage reference terminal 112. At 1514, the method 900 alsoincludes generating a third analog voltage signal ANALOG V3 at a thirdanalog voltage output 536 of the voltage measurement conditioningcircuit 510 based on the third sensed voltage signal SENSED V3 at thethird voltage sense terminal 534 in reference to the voltage referencesignal at the voltage reference terminal 112.

At 1516, a first sensed current signal SENSED I is received at a firstpositive current sense terminal 550 (e.g., FIG. 5) of the currentmeasurement conditioning circuit 546 from a first current sensor 556associated with the string of PV sub-modules 116 (e.g., FIG. 1). At1518, the method 900 also includes receiving a first current referencesignal at a first negative current sense terminal 552 of the currentmeasurement conditioning circuit 546 from the first current sensor 556.At 1520, a second sensed current signal SENSED I2 is received at asecond positive current sense terminal 564 of the current measurementconditioning circuit 546 from a second current sensor 570 associatedwith the string of PV sub-modules 116. At 1522, the method 900 alsoincludes receiving a second current reference signal at a secondnegative current sense terminal 566 of the current measurementconditioning circuit 546 from the second current sensor 570. At 1524, afirst analog current signal ANALOG I is generated at a first analogcurrent output 554 of the current measurement conditioning circuit 546based on the first sensed current signal SENSED I at the first positivecurrent sense terminal 550 in reference to the first current referencesignal at the first negative current sense terminal 552. At 1526, themethod 900 also includes generating a second analog current signalANALOG I2 at a second analog current output 568 of the currentmeasurement conditioning circuit 546 based on the second sensed currentsignal SENSED I2 at the second positive current sense terminal 564 inreference to the second current reference signal at the second negativecurrent sense terminal 566. At 1528, a sensed temperature signal SENSEDT is received at a positive temperature sense terminal 584 of thetemperature measurement conditioning circuit 580 from a temperaturesensor 590 associated with the string of PV sub-modules 116. At 1530,the method 900 also includes receiving a temperature reference signal ata negative temperature sense terminal 586 of the temperature measurementconditioning circuit 580 from the temperature sensor 590. At 1532, ananalog temperature signal ANALOG T is generated at an analog temperatureoutput 588 of the temperature measurement conditioning circuit 580 basedon the sensed temperature signal SENSED T at the positive temperaturesense terminal 584 in reference to the temperature reference signal atthe negative temperature sense terminal 586.

At 1534, the method 900 also includes receiving the analog voltagesignal ANALOG V at an analog voltage input 714 (e.g., FIG. 7) of themultiplexer circuit 710. At 1536, the second analog voltage signalANALOG V2 is received at a second analog voltage input 716 of themultiplexer circuit 710. At 1538, the method 900 also includes receivingthe third analog voltage signal ANALOG V3 at a third analog voltageinput 718 of the multiplexer circuit 710. At 1540, the first analogcurrent signal ANALOG I is received at a first analog current input 720of the multiplexer circuit 710. At 1542, the method 900 also includesreceiving the second analog current signal ANALOG I2 at a second analogcurrent input 722 of the multiplexer circuit 710. At 1544, the analogtemperature signal ANALOG T is received at an analog temperature input724 of the multiplexer circuit 710. At 1546, the method 900 alsoincludes generating a measurement select signal MEAS SELECT at ameasurement select output 728 of the microcontroller circuit 106 (e.g.,FIG. 1) to enable selection of a select analog signal from multipleanalog signals received at multiple analog inputs to the multiplexercircuit 710 for routing the select analog signal to an analogmeasurement output 730. At 1548, the measurement select signal MEASSELECT is received at a measurement select input 726 of the multiplexercircuit 710. At 1550, the method 900 also includes routing the analogvoltage input 714, the second analog voltage input 716, the third analogvoltage input 718, the first analog current input 720, the second analogcurrent input 722, or the analog temperature input 724 to the analogmeasurement output 730 in response to the measurement select signal MEASSELECT at the measurement select input 726 to provide an analogmeasurement signal ANALOG MEAS to the analog measurement output 730. At1552, the digital measurement data DIG MEAS DATA is generated at adigital measurement data output 114 of the analog-to-digital convertercircuit 712 based on the analog measurement signal ANALOG MEAS at ananalog measurement input 732.

In another example, the string of PV sub-modules 116 (e.g., FIG. 1)includes first, second, and third PV sub-modules 1702, 1704, 1706 (e.g.,FIG. 17). In this example, the method 900 also includes receiving thesensed voltage signal SENSED V from a positive DC power terminal 1714 ofthe first PV sub-module 1702 at the voltage sense terminal 110 of thevoltage measurement conditioning circuit 510 (e.g., FIG. 5). The method900 also includes receiving the second sensed voltage signal SENSED V2from a positive DC power terminal 1722 of the second PV sub-module 1704at the second voltage sense terminal 522 of the voltage measurementconditioning circuit 510. The method 900 also includes receiving thethird sensed voltage signal SENSED V3 from a positive DC power terminal1728 of the third PV sub-module 1706 at the third voltage sense terminal534 of the voltage measurement conditioning circuit 510. The method 900also includes receiving the voltage reference signal from a negative DCpower terminal 1730 of the third PV sub-module 1706 at the voltagereference terminal 112 of the voltage measurement conditioning circuit510.

In another example, the method 900 also includes generating powermeasurement data associated with the string of PV sub-modules 116 (e.g.,FIG. 1) at the microcontroller circuit 106 based on the digitalmeasurement data DIG MEAS DATA associated with the sensed voltage signalSENSED V and the digital measurement data DIG MEAS DATA associated withthe first sensed current signal SENSED I or the second sensed currentsignal SENSED I2. The measurement data stream MEAS DATA STREAM is alsobased on the power measurement data such that the power measurement datais represented within the measurement data stream MEAS DATA STREAM andthe output communication signal COMM SIG OUT.

In another example, the string of PV sub-modules 116 (e.g., FIG. 1)includes a positive DC power terminal 1714 (e.g., FIG. 17) coupled witha positive DC power line 1718 of a DC bus 1720 and a negative DC powerterminal 1730 coupled with a negative DC power line 1732 of the DC bus1720. In one implementation, the first current sensor 556 (e.g., FIG. 5)includes positive and negative terminals. The first positive currentsense terminal 550 of the current measurement conditioning circuit 546is coupled with the positive terminal and the first negative currentsense terminal 552 of the current measurement conditioning circuit 546is coupled with the negative terminal. In this implementation, themethod 900 also includes sensing current passing through the positive DCpower line 1718 between the DC bus 1720 and the positive DC powerterminal 1714 of the string of PV sub-modules 116 at the first currentsensor 556. The method 900 also includes generating the first sensedcurrent signal SENSED I at the first current sensor 556 based on thesensed current. In another implementation, the second current sensor 570includes positive and negative terminals. The second positive currentsense terminal 564 of the current measurement conditioning circuit 546is coupled with the positive terminal and the second negative currentsense terminal 566 of the current measurement conditioning circuit 546is coupled with the negative terminal. In this implementation, themethod 900 also includes sensing current passing through the negative DCpower line 1732 between the negative DC power terminal 1730 of thestring of PV sub-modules 116 and the DC bus 1720 at the second currentsensor 570. The method 900 also includes generating the second sensedcurrent signal SENSED I2 at the second current sensor 570 based on thesensed current.

In another example, the temperature sensor 590 (e.g., FIG. 5) includespositive and negative terminals. The positive temperature sense terminal584 of the temperature measurement conditioning circuit 580 is coupledwith the positive terminal and the negative temperature sense terminal586 of the temperature measurement conditioning circuit 580 is coupledwith the negative terminal. In this example, the method 900 alsoincludes sensing a temperature associated with the PV module 100 (e.g.,FIG. 1) at the temperature sensor 590. The method 900 also includesgenerating the sensed temperature signal SENSED T at the temperaturesensor 590 based on the sensed temperature.

FIGS. 9 and 16 show another example of the method 900 in which thetransmitter circuit 108 (e.g., FIG. 1) includes a crystal oscillatorcircuit 810 (e.g., FIG. 8), a digital-to-analog converter circuit 812, amodulator circuit 814, and a power amplifier circuit 816. In thisexample, at 1602, the method 900 also includes generating the modulationclock signal MOD CLK at a modulation clock output 128 of the crystaloscillator circuit 810. At 1604, an analog measurement signal ANALOGMEAS is generated at an analog measurement output 820 of thedigital-to-analog converter circuit 812 based on the measurement datastream MEAS DATA STREAM at a measurement data stream input 126 inresponse to the modulation clock signal MOD CLK at a second modulationclock input 818. At 1606, the method 900 also includes generating amodulated measurement signal MOD MEAS at a modulated measurement output826 of the modulator circuit 814 based on the analog measurement signalANALOG MEAS at an analog measurement input 822 in response to themodulation clock signal MOD CLK at a modulation clock input 120. At1608, the output communication signal COMM SIG OUT is generated at thepower amplifier circuit 816 based on the modulated measurement signalMOD MEAS at a third modulated measurement input 828. At 1610, the method900 also includes transmitting the output communication signal COMM SIGOUT to the communication interface circuit 136 via positive and negativeoutput communication terminals 132, 134 of the power amplifier circuit816 in response to the transmit select signal XMIT SELECT at a transmitselect input 130. The modulation clock output 128 of the transmittercircuit 108 includes the modulation clock output 128 of the crystaloscillator circuit 810. The measurement data stream input 126 of thetransmitter circuit 108 includes the measurement data stream input 126of the digital-to-analog converter circuit 812. The positive andnegative output communication terminals 132, 134 of the transmittercircuit 108 include the positive and negative output communicationterminals 132, 134 of the power amplifier circuit 816. The transmitselect input 130 of the transmitter circuit 108 includes the transmitselect input 130 of the power amplifier circuit 816.

In another example; the communication interface circuit 136 (e.g.,FIG. 1) includes a positive DC power terminal 1802 (e.g., FIG. 18)coupled with a positive DC power line 1718 (e.g., FIG. 17) of a DC bus1720 and a negative DC power terminal 1804. The string of PV sub-modules116 includes a positive DC power terminal 1714 coupled with the negativeDC power terminal 1804 of the communication interface circuit 136 and anegative DC power terminal 1730 coupled with a negative DC power line1732 of the DC bus 1720. The measurement data stream MEAS DATA STREAM,analog measurement signal ANALOG MEAS, and modulated measurement signalMOD MEAS are formed such that the output communication signal COMM SIGOUT is a power line communication signal. In this example, the method900 also includes transmitting the PLC signal from the communicationinterface circuit 136 to a remote receiver circuit 1806 via the positiveand negative DC power lines 1718, 1732 of the DC bus 1720 by applyingthe output communication signal COMM SIG OUT received from the poweramplifier circuit 816 to the positive and negative DC power terminals1802, 1804 of the communication interface circuit 136. In oneimplementation, the PLC signal is a spread frequency shift keyingwaveform. In one example, the S-FSK waveform is compliant with PLCprotocol requirements of SunSpec Interoperability Specification,Communication Signal for Rapid Shutdown, Version 34. In this example,the method 900 also includes transmitting the output communicationsignal COMM SIG OUT from the power amplifier circuit 816 to thecommunication interface circuit 136 during a zero energy period of arepetitive data frame specified in the PLC protocol requirements of theSunSpec Interoperability Specification.

In another example, the communication interface circuit 136 (e.g.,FIG. 1) includes an antenna 1902 (e.g., FIG. 19). In this example, themethod 900 also includes generating a wireless communication signal atthe communication interface circuit 136 based on the outputcommunication signal COMM SIG OUT received from the power amplifiercircuit 816. The method 900 also includes transmitting the wirelesscommunication signal from the communication interface circuit 136 to aremote receiver circuit 1904 via the antenna 1902.

In another example, the method 900 also includes generating a wiredcontrol line communication signal at the communication interface circuit136 (e.g., FIG. 1) based on the output communication signal COMM SIG OUTreceived from the power amplifier circuit 816 (e.g., FIG. 8). The method900 also includes transmitting the wired control line communicationsignal from the communication interface circuit 136 to a remotereceiver/transmitter circuit 2006 (e.g., FIG. 20) via wired transmissionlines coupling the communication interface circuit 136 to the remotereceiver/transmitter circuit 2006.

In another example, the method 900 also includes using the modulationclock signal MOD CLK to sample the measurement data stream MEAS DATASTREAM at the measurement data stream input 126 (e.g., FIG. 1) of thedigital-to-analog converter circuit 812 (e.g., FIG. 8) of thetransmitter circuit 108 to form the analog measurement signal ANALOGMEAS at the analog measurement output 820. In another example, themethod 900 also includes using the modulation clock signal MOD CLK tosample the analog measurement signal ANALOG MEAS at the analogmeasurement input 822 of the modulator circuit 814 to form the modulatedmeasurement signal MOD MEAS at the modulated measurement output 826.

FIG. 17 shows an example of a PV module 100 that includes acommunication interface circuit 136, a second PV sub-module 1704, athird PV sub-module 1706, and a monitoring circuit 102. Thecommunication interface circuit 136 includes positive and negative inputcommunication terminals 1708, 1710 and an external interface 1712. Thefirst PV sub-module 1702 includes positive and negative DC powerterminals 1714, 1716. The second PV sub-module 1704 includes a positiveDC power terminal 1722 coupled with the negative DC power terminal 1716of the first PV sub-module 1702 and a negative DC power terminal 1724.The third PV sub-module 1706 includes a positive DC power terminal 1728coupled with the negative DC power terminal 1724 of the second PVsub-module 1704 and a negative DC power terminal 1730. The monitoringcircuit 102 includes positive and negative output communicationterminals 132, 134 coupled with the positive and negative inputcommunication terminals 1708, 1710, a voltage sense terminal 110 coupledwith the positive DC power terminal 1714 of the first PV sub-module1702, and a voltage reference terminal 112 coupled with the negative DCpower terminal 1730 of the third PV sub-module 1706. The communicationinterface circuit 136 routes an output communication signal COMM SIG OUTat the positive and negative input communication terminals 1708, 1710 tothe external interface 1712. The first PV sub-module 1702 generates afirst PV output voltage across the positive and negative DC powerterminals 1714, 1716 in response to exposure to light. The first PVsub-module 1702 couples with a positive DC power line 1718 of a DC bus1720 associated with the PV module 100 via the positive DC powerterminal 1714. The second PV sub-module 1704 generates a second PVoutput voltage across the positive and negative DC power terminals 1722,1724 in response to exposure to light. The third PV sub-module 1706generates a third PV output voltage across the positive and negative DCpower terminals 1728, 1730 in response to exposure to light. The thirdPV sub-module 1706 couples with a negative DC power line 1732 of the DCbus 1720 via the negative DC power terminal 1730. The monitoring circuit102 generates digital measurement data DIG MEAS DATA based on a sensedvoltage signal SENSED V at the voltage sense terminal 110 in referenceto a voltage reference signal at the voltage reference terminal 112 suchthat the sensed voltage signal SENSED V is represented within thedigital measurement data DIG MEAS DATA. The monitoring circuit 102generates a measurement data stream MEAS DATA STREAM based on thedigital measurement data DIG MEAS DATA such that the sensed voltagesignal SENSED V is represented within the measurement data stream MEASDATA STREAM. The monitoring circuit 102 generates a transmit selectsignal XMIT SELECT based on the measurement data stream MEAS DATASTREAM. The monitoring circuit 102 generates the output communicationsignal COMM SIG OUT based on the measurement data stream MEAS DATASTREAM such that the sensed voltage signal SENSED V is representedwithin the output communication signal COMM SIG OUT. The monitoringcircuit 102 transmits the output communication signal COMM SIG OUT tothe communication interface circuit 136 via the positive and negativeoutput communication terminals 132, 134 in response to the transmitselect signal XMIT SELECT.

In another example, the monitoring circuit 102 also includes a secondvoltage sense terminal 522 coupled with the positive DC power terminal1722 of the second PV sub-module 1704. The digital measurement data DIGMEAS DATA is also based on a second sensed voltage signal SENSED V2 atthe second voltage sense terminal 522 in reference to the voltagereference signal at the voltage reference terminal 112 such that thesecond sensed voltage signal SENSED V2 is represented within the digitalmeasurement data DIG MEAS DATA, the measurement data stream MEAS DATASTREAM, and the output communication signal COMM SIG OUT. In anotherexample, the monitoring circuit 102 also includes a third voltage senseterminal 534 coupled with the positive DC power terminal 1728 of thethird PV sub-module 1706. The digital measurement data DIG MEAS DATA isalso based on a third sensed voltage signal SENSED V3 at the thirdvoltage sense terminal 534 in reference to the voltage reference signalat the voltage reference terminal 112 such that the third sensed voltagesignal SENSED V3 is represented within the digital measurement data DIGMEAS DATA, the measurement data stream MEAS DATA STREAM, and the outputcommunication signal COMM SIG OUT.

FIG. 18 shows an example of the PV module 100 in which the outputcommunication signal COMM SIG OUT at the communication interface circuit136 is communicated externally via a power line communication signal.The external interface 1712 includes a positive DC power terminal 1802coupled with the positive DC power line 1718 of the DC bus 1720 and anegative DC power terminal 1804 coupled with the positive DC powerterminal 1714 of the first PV sub-module 1702. The communicationinterface circuit 136 routes the positive DC power line 1718 at thepositive DC power terminal 1802 to the negative DC power terminal 1804.The communication interface circuit 1718 transmits the PLC signal to aremote receiver circuit 1806 via the positive and negative DC powerlines 1718, 1732 of the DC bus 1720 by applying the output communicationsignal COMM SIG OUT at the positive and negative input communicationterminals 1708, 1710 to the positive and negative DC power terminals1802, 1804. In one implementation, the PLC signal is a spread frequencyshift keying waveform.

FIG. 19 shows an example of the PV module 100 in which the outputcommunication signal COMM SIG OUT at the communication interface circuit136 is communicated externally via a wireless communication signal. Theexternal interface 1712 includes an antenna 1902. The communicationinterface circuit 136 generates the wireless communication signal basedon the output communication signal COMM SIG OUT at the positive andnegative input communication terminals 1708, 1710. The communicationinterface circuit 136 transmits the wireless communication signal to aremote receiver circuit 1904 via the antenna 1902.

FIG. 20 shows an example of the PV module 100 in which the outputcommunication signal COMM SIG OUT at the communication interface circuit136 is communicated externally via a wired control line communicationsignal. The communication interface circuit 136 generates the wiredcontrol line communication signal based on the output communicationsignal COMM SIG OUT at the positive and negative input communicationterminals 1708, 1710. The external interface 1712 includes a positivecontrol line terminal 2002 and a negative control line terminal 2004.The communication interface circuit 136 transmits the wired control linecommunication signal to a remote receiver/transmitter circuit 2006 via awired control line between the external interface 1712 and the remotereceiver/transmitter circuit 2006 by applying the wired control linecommunication signal to the positive and negative control line terminals2002, 2004.

FIG. 17 also shows the PV module 100 receiving communication signals.The communication interface circuit 136 also includes positive andnegative output communication terminals 1734, 1736. The communicationinterface circuit 136 routes an input communication signal COMM SIG INat the external interface 1712 to the positive and negative outputcommunication terminals 1734, 1736. The monitoring circuit 102 alsoincludes positive and negative input communication terminals 144, 146coupled with the positive and negative output communication terminals1734, 1736 of the communication interface circuit 136. The monitoringcircuit 102 generates an input communication data stream INPUT COMM DATASTREAM based on the input communication signal COMM SIG IN from thecommunication interface circuit 136 at the positive and negative inputcommunication terminals 144, 146. The monitoring circuit 102 processesthe input communication data stream INPUT COMM DATA STREAM to detectmodulated data carried by the input communication signal COMM SIG IN andrepresented within the input communication data stream INPUT COMM DATASTREAM. The monitoring circuit 102 generates the transmit select signalXMIT SELECT in response to detecting, for a predetermined time, anabsence of the modulated data in the input communication data streamINPUT COMM DATA STREAM representing the input communication signal COMMSIG IN.

FIG. 18 shows an example of the PV module 100 in which the inputcommunication signal COMM SIG IN at the communication interface circuit136 is based on a power line communication signal. The externalinterface 1712 includes a positive DC power terminal 1802 coupled withthe positive DC power line 1718 of the DC bus 1720 and a negative DCpower terminal 1804 coupled with the positive DC power terminal 1714 ofthe first PV sub-module 1702. The communication interface circuit 136routes the positive DC power line 1718 at the positive DC power terminal1802 to the negative DC power terminal 1804. The communication interfacecircuit 136 receives the PLC signal at the positive and negative DCpower terminals 1802, 1804 from a remote transmitter circuit 1806 viathe positive and negative DC power lines 1718, 1732 of the DC bus 1720.The communication interface circuit 136 generates the inputcommunication signal COMM SIG IN at the positive and negative outputcommunication terminals 1734, 1736 based on data carried by the PLCsignal transmitted via the DC bus 1720. In one implementation, the PLCsignal is a spread frequency shift keying waveform.

FIG. 19 shows an example of the PV module 100 in which the inputcommunication signal COMM SIG IN at the communication interface circuit136 is based on a wireless communication signal. The external interface1712 includes an antenna 1902 that receives the wireless communicationsignal from a remote transmitter circuit 1904. The communicationinterface circuit 136 generates the input communication signal COMM SIGIN at the positive and negative output communication terminals 1734,1736 based on data carried by the wireless communication signal.

FIG. 20 shows an example of the PV module 100 in which the inputcommunication signal COMM SIG IN at the communication interface circuit136 is based on a wired control line communication signal. The externalinterface 1712 includes positive and negative control line terminals2002, 2004 that receive the wired control line communication signal froma remote receiver/transmitter circuit 2006 via a wired control linebetween the external interface 1712 and the remote receiver/transmittercircuit 2006. The communication interface circuit 136 generates theinput communication signal COMM SIG IN at the positive and negativeoutput communication terminals 1734, 1736 based on data carried by thewired control line communication signal.

FIG. 17 also shows an example of the PV module 100 with a current sensor556/570. The current sensor 556/570 includes positive and negativeterminals. In this example, the monitoring circuit 102 also includes apositive current sense terminal 550/564 coupled with the positiveterminal and a negative current sense terminal 552/566 coupled with thenegative terminal. The current sensor 556/570 senses current passingthrough the PV module 100 between the positive DC power line 1718 of theDC bus 1720 and the negative DC power line 1732 of the DC bus 1720. Thecurrent sensor 556/570 generates a sensed current signal SENSED I/SENSEDI2 based on the sensed current. The digital measurement data DIG MEASDATA is also based on the sensed current signal SENSED I/SENSED I2 atthe positive current sense terminal 550/564 in reference to a currentreference signal at the negative current sense terminal 552/566 suchthat the sensed current signal SENSED I/SENSED I2 is represented withinthe digital measurement data DIG MEAS DATA, the measurement data streamMEAS DATA STREAM, and the output communication signal COMM SIG OUT. Inone implementation, the current sensor 556 senses current passingthrough the positive DC power line 1718 coupled with the positive DCpower terminal 1714 of the first PV sub-module 1702. In anotherimplementation, the current sensor 570 senses current passing throughthe negative DC power terminal 1730 of the of the third PV sub-module1706 coupled with the negative DC power line 1732.

In another example, the monitoring circuit 102 generates powermeasurement data associated with the PV module 100 based on the digitalmeasurement data DIG MEAS DATA associated with the sensed voltage signalSENSED V and the digital measurement data DIG MEAS DATA associated withthe sensed current signal SENSED I/SENSED I2. The measurement datastream MEAS DATA STREAM is also based on the power measurement data suchthat the power measurement data is represented within the measurementdata stream MEAS DATA STREAM and the output communication signal COMMSIG OUT.

In another example, the PV module 100 includes a temperature sensor 590.The temperature sensor 590 includes positive and negative terminals. Inthis example, the monitoring circuit 102 includes a positive temperaturesense terminal 584 coupled with the positive terminal and a negativetemperature sense terminal 586 coupled with the negative terminal. Thetemperature sensor 590 senses a temperature associated with the PVmodule 100 and generates a sensed temperature signal SENSED T based onthe sensed temperature. The digital measurement data DIG MEAS DATA isalso based on the sensed temperature signal SENSED T at the positivetemperature sense terminal 584 in reference to a temperature referencesignal at the negative temperature sense terminal 586 such that thesensed temperature signal SENSED T is represented within the digitalmeasurement data DIG MEAS DATA, the measurement data stream MEAS DATASTREAM, and the output communication signal COMM SIG OUT.

FIG. 21 shows an example of a PV module 100 in which the first PVsub-module 1702 includes a first string of PV cells 2102 and a firstbypass diode 2104. The first string of PV cells 2102 includes a positiveterminal 2106 coupled with the positive DC power terminal 1714 of thefirst PV sub-module 1702 and a negative terminal 2108 coupled with thenegative DC power terminal 1716 of the first PV sub-module 1702. Thefirst string of PV cells 2102 generates the first PV output voltageacross the positive and negative terminals 2106, 2108 in response to theexposure to the light. The first bypass diode 2104 includes a positiveterminal 2110 coupled with the positive DC power terminal 1714 of thefirst PV sub-module 1702 and a negative terminal 2112 coupled with thenegative DC power terminal 1716 of the first PV sub-module 1702. Thefirst bypass diode 2104 bypasses the first string of PV cells 2102 whenthe first string of PV cells 2102 is exposed to the light andexperiencing shaded conditions.

In another example, the second PV sub-module 1704 includes a secondstring of PV cells 2114 and a second bypass diode 2116. The secondstring of PV cells 2114 includes a positive terminal 2118 coupled withthe positive DC power terminal 1722 of the second PV sub-module 1704 anda negative terminal 2120 coupled with the negative DC power terminal1724 of the second PV sub-module 1704. The second string of PV cells2114 generates the second PV output voltage across the positive andnegative terminals 2118, 2120 in response to the exposure to the light.The second bypass diode 2116 includes a positive terminal 2122 coupledwith the positive DC power terminal 1722 of the second PV sub-module1704 and a negative terminal 2124 coupled with the negative DC powerterminal 1724 of the second PV sub-module 1704. The second bypass diode2116 bypasses the second string of PV cells 2114 when the second stringof PV cells 2114 is exposed to the light and experiencing shadedconditions.

In another example, the third PV sub-module 1706 includes a third stringof PV cells 2126 and a third bypass diode 2128. The third string of PVcells 2126 includes a positive terminal 2130 coupled with the positiveDC power terminal 1728 of the third PV sub-module 1706 and a negativeterminal 2132 coupled with the negative DC power terminal 1730 of thethird PV sub-module 1706. The third string of PV cells 2126 generatesthe third PV output voltage across the positive and negative terminals2130, 2132 in response to the exposure to the light. The third bypassdiode 2128 includes a positive terminal 2134 coupled with the positiveDC power terminal 1728 of the third PV sub-module 1706 and a negativeterminal 2136 coupled with the negative DC power terminal 1730 of thethird PV sub-module 1706. The third bypass diode 2128 bypasses the thirdstring of PV cells 2126 when the third string of PV cells 2126 isexposed to the light and experiencing shaded conditions.

FIG. 21 shows an example of a PV module 100 in which the first PVsub-module 1702 includes a first string of PV cells 2102, a first PVsub-module controller circuit 2202, and a first capacitor 2204. Thefirst string of PV cells 2102 includes a positive terminal 2106 and anegative terminal 2108 coupled with the negative DC power terminal 1716of the first PV sub-module 1702. The first string of PV cells 2102generates a first DC string voltage across the positive and negativeterminals 2106, 2108 in response to exposure to the light. The first PVsub-module controller circuit 2202 includes a positive terminal 2206coupled with the positive terminal 2106 of the first string of PV cells2102, a negative terminal 2208 coupled with the negative terminal 2108of the first string of PV cells 2102, and an output terminal 2210coupled with the positive DC power terminal 1714 of the first PVsub-module 1702. The first PV sub-module controller circuit 2202generates a first DC output voltage VOUT1 across the output and negativeterminals 2210, 2208 based on the first DC string voltage across thepositive and negative terminals 2106, 2108. The first capacitor 2204includes a positive terminal 2212 coupled with the output terminal 2210of the first PV sub-module controller circuit 2202 and a negativeterminal 2214 coupled with the negative terminal 2208 of the first PVsub-module controller circuit 2202. The first capacitor 2204 chargeswhen a first DC voltage across the positive and negative terminals 2212,2214 is positive and discharges when the first DC voltage across thepositive and negative terminals 2212, 2214 is negative.

In another example, the second PV sub-module 1704 includes a secondstring of PV cells 2114, a second PV sub-module controller circuit 2216,and a second capacitor 2218. The second string of PV cells 2114 includesa positive terminal 2118 and a negative terminal 2120 coupled with thenegative DC power terminal 1724 of the second PV sub-module 1704. Thesecond string of PV cells 2114 generates a second DC string voltageacross the positive and negative terminals 2118, 2120 in response toexposure to the light. The second PV sub-module controller circuit 2216includes a positive terminal 2220 coupled with the positive terminal2118 of the second string of PV cells 2114, a negative terminal 2222coupled with the negative terminal 2120 of the second string of PV cells2114, and an output terminal 2224 coupled with the positive DC powerterminal 1722 of the second PV sub-module 1704. The second PV sub-modulecontroller circuit 2216 generates a second DC output voltage VOUT2across the output and negative terminals 2224, 2222 based on the secondDC string voltage across the positive and negative terminals 2118, 2120.The second capacitor 2218 includes a positive terminal 2226 coupled withthe output terminal 2224 of the second PV sub-module controller circuit2216 and a negative terminal 2228 coupled with the negative terminal2222 of the second PV sub-module controller circuit 2216. The secondcapacitor 2218 charges when a second DC voltage across the positive andnegative terminals 2226, 2228 is positive and discharges when the secondDC voltage across the positive and negative terminals 2226, 2228 isnegative.

In another example, the third PV sub-module 1706 includes a third stringof PV cells 2126, a third PV sub-module controller circuit 2230, and athird capacitor 2232. The third string of PV cells 2126 includes apositive terminal 2130 and a negative terminal 2132 coupled with thenegative DC power terminal 1730 of the third PV sub-module 1706. Thethird string of PV cells 2126 generates a third DC string voltage acrossthe positive and negative terminals 2130, 2132 in response to exposureto the light. The third PV sub-module controller circuit 2230 includes apositive terminal 2234 coupled with the positive terminal 2130 of thethird string of PV cells 2126, a negative terminal 2236 coupled with thenegative terminal 2132 of the third string of PV cells 2126, and anoutput terminal 2238 coupled with the positive DC power terminal 1728 ofthe third PV sub-module 1706. The third PV sub-module controller circuit2230 generates a third DC output voltage VOUT3 across the output andnegative terminals 2238, 2236 based on the third DC string voltageacross the positive and negative terminals 2130, 2132. The thirdcapacitor 2232 includes a positive terminal 2240 coupled with the outputterminal 2238 of the third PV sub-module controller circuit 2230 and anegative terminal 2242 coupled with the negative terminal 2236 of thethird PV sub-module controller circuit 2230. The third capacitor 2232charges when a third DC voltage across the positive and negativeterminals 2240, 2242 is positive and discharges when the third DCvoltage across the positive and negative terminals 2240, 2242 isnegative.

Modifications are possible in the described examples, and other examplesare possible, within the scope of the claims. The various circuitsdescribed above can be implemented using any suitable combination ofdiscrete components, ICs, processors, memory, storage devices, andfirmware.

The following is claimed:
 1. A monitoring circuit for a photovoltaic(PV) module, comprising: a measurement conditioning circuit, including avoltage sense terminal, a voltage reference terminal, and a digitalmeasurement data output; a microcontroller circuit, including a digitalmeasurement data input coupled with the digital measurement data output,a modulation clock input, a measurement data stream output, and atransmit select output; and a transmitter circuit, including ameasurement data stream input coupled with the measurement data streamoutput, a modulation clock output coupled with the modulation clockinput, a transmit select input coupled with the transmit select output,and positive and negative output communication terminals.
 2. Themonitoring circuit of claim 1, wherein the measurement conditioningcircuit, microcontroller circuit, and transmitter circuit are includedin an integrated circuit (IC).
 3. The monitoring circuit of claim 1,wherein the microcontroller circuit includes an input communication datastream input and a demodulation clock input, the monitoring circuitfurther comprising: a receiver circuit, including positive and negativeinput communication terminals an input communication data stream outputcoupled with the input communication data stream input, and ademodulation clock output coupled with the demodulation clock input. 4.The monitoring circuit of claim 3, wherein the microcontroller circuitincludes a permission to operate (PTO) output, the monitoring circuitfurther comprising: a PTO distribution circuit, including a PTO inputcoupled with the PTO output, a local PTO output terminal, and a remotePTO output terminal.
 5. The monitoring circuit of claim 3, the receivercircuit comprising: a bandpass filter circuit, including the positiveand negative input communication terminals of the receiver circuit and afiltered input communication output; a crystal oscillator circuit,including the demodulation clock output of the receiver circuit; and ananalog-to-digital converter circuit, including a filtered inputcommunication input coupled with the filtered input communicationoutput, a second demodulation clock input coupled with the demodulationclock output, and the input communication data stream output of thereceiver circuit.
 6. The monitoring circuit of claim 1, the measurementconditioning circuit comprising: a voltage measurement conditioningcircuit, including the voltage sense terminal of the measurementconditioning circuit, the voltage reference terminal of the measurementconditioning circuit, and an analog voltage output; and ananalog-to-digital converter circuit, including an analog voltage inputcoupled with the analog voltage output and a digital voltage measurementoutput coupled with a digital voltage measurement input of themicrocontroller circuit; wherein the digital measurement data output ofthe measurement conditioning circuit includes the digital voltagemeasurement output, wherein the digital measurement data input of themicrocontroller circuit includes the digital voltage measurement input.7. The monitoring circuit of claim 6, wherein the voltage measurementconditioning circuit also includes a second voltage sense terminal and asecond analog voltage output, the measurement conditioning circuitfurther comprising: a second analog-to-digital converter circuit,including a second analog voltage input coupled with the second analogvoltage output and a second digital voltage measurement output coupledwith a second digital voltage measurement input of the microcontrollercircuit; wherein the digital measurement data output of the measurementconditioning circuit includes the second digital voltage measurementoutput, wherein the digital measurement data input of themicrocontroller circuit includes the second digital voltage measurementinput.
 8. The monitoring circuit of claim 7, wherein the voltagemeasurement conditioning circuit also includes a third voltage senseterminal and a third analog voltage output, the conditioning circuitfurther comprising: a third analog-to-digital converter circuit,including a third analog voltage input coupled with the third analogvoltage output and a third digital voltage measurement output coupledwith a third digital voltage measurement input of the microcontrollercircuit; wherein the digital measurement data output of the measurementconditioning circuit includes the third digital voltage measurementoutput, wherein the digital measurement data input of themicrocontroller circuit includes the third digital voltage measurementinput.
 9. The monitoring circuit of claim 6, the measurementconditioning circuit further comprising: a current measurementconditioning circuit, including positive and negative current senseterminals and an analog current output; and a second analog-to-digitalconverter circuit, including an analog current input coupled with theanalog current output and a digital current measurement output coupledwith a digital current measurement input of the microcontroller circuit;wherein the digital measurement data output of the measurementconditioning circuit includes the digital current measurement output,wherein the digital measurement data input of the microcontrollercircuit includes the digital current measurement input.
 10. Themonitoring circuit of claim 9, wherein the current measurementconditioning circuit also includes a second positive current senseterminal, a second negative current sense terminal, and a second analogcurrent output, the measurement conditioning circuit further comprising:a third analog-to-digital converter circuit, including a second analogcurrent input coupled with the second analog current output and a seconddigital current measurement output coupled with a second digital currentmeasurement input of the microcontroller circuit; wherein the digitalmeasurement data output of the measurement conditioning circuit includesthe second digital current measurement output, wherein the digitalmeasurement data input of the microcontroller circuit includes thesecond digital current measurement input.
 11. The monitoring circuit ofclaim 6, the measurement conditioning circuit further comprising: atemperature measurement conditioning circuit, including positive andnegative temperature sense terminals and an analog temperature output;and a second analog-to-digital converter circuit, including an analogtemperature input coupled with the analog temperature output and adigital temperature measurement output coupled with a digitaltemperature measurement input of the microcontroller circuit; whereinthe digital measurement data output of the measurement conditioningcircuit includes the digital temperature measurement output, wherein thedigital measurement data input of the microcontroller circuit includesthe digital temperature measurement input.
 12. The monitoring circuit ofclaim 1, the measurement conditioning circuit comprising: a voltagemeasurement conditioning circuit, including the voltage sense terminalof the measurement conditioning circuit, a second voltage senseterminal, a third voltage sense terminal, the voltage reference terminalof the measurement conditioning circuit, an analog voltage output, asecond analog voltage output, and a third analog voltage output; acurrent measurement conditioning circuit, including first positive andnegative current sense terminals, second positive and negative currentsense terminals, a first analog current output, and a second analogcurrent output; a temperature measurement conditioning circuit,including positive and negative temperature sense terminals and ananalog temperature output; a multiplexer circuit, including an analogvoltage input coupled with the analog voltage output, a second analogvoltage input coupled with the second analog voltage output, a thirdanalog voltage input coupled with the third analog voltage output, afirst analog current input coupled with the first analog current output,a second analog current input coupled with the second analog currentoutput, an analog temperature input coupled with the analog temperatureoutput, a measurement select input coupled with a measurement selectoutput of the microcontroller circuit, and an analog measurement output;and an analog-to-digital converter circuit, including an analogmeasurement input coupled with the analog measurement output and thedigital measurement data output of the measurement conditioning circuitcoupled with the digital measurement data input.
 13. The monitoringcircuit of claim 1, the transmitter circuit comprising: a crystaloscillator circuit, including the modulation clock output of thetransmitter circuit coupled with the modulation clock input of themicrocontroller circuit; a digital-to-analog converter circuit,including the measurement data stream input of the transmitter circuitcoupled with the measurement data stream output, a second modulationclock input coupled with the modulation clock output, and an analogmeasurement output; a modulator circuit, including an analog measurementinput coupled with the analog measurement output, a modulation clockinput coupled with the modulation clock output, and a modulatedmeasurement output; and a power amplifier circuit, including a thirdmodulated measurement input coupled with the modulated measurementoutput, the transmit select input of the transmitter circuit coupledwith the transmit select output, and the positive and negative outputcommunication terminals of the transmitter circuit.
 14. A method formonitoring a photovoltaic (PV) module, comprising: receiving a sensedvoltage signal at a voltage sense terminal of a measurement conditioningcircuit from a string of PV sub-modules associated with the PV module;receiving a voltage reference signal at a voltage reference terminal ofthe measurement conditioning circuit from the string of PV sub-modules;generating digital measurement data at a digital measurement data outputof the measurement conditioning circuit based on the sensed voltagesignal in reference to the voltage reference signal such that the sensedvoltage signal is represented within the digital measurement data;generating a modulation clock signal at a modulation clock output of atransmitter circuit; generating a measurement data stream at ameasurement data stream output of a microcontroller circuit based on thedigital measurement data at a digital measurement data input and themodulation clock signal at a modulation clock input such that the sensedvoltage signal is represented within the measurement data stream;generating an output communication signal at the transmitter circuitbased on the modulation clock signal and the measurement data stream ata measurement data stream input such that the sensed voltage signal isrepresented within the output communication signal; generating atransmit select signal at a transmit select output of themicrocontroller circuit based on the measurement data stream; andtransmitting the output communication signal from the transmittercircuit to a communication interface circuit via positive and negativeoutput communication terminals in response to the transmit select signalat a transmit select input of the transmitter circuit.
 15. The method ofclaim 14, further comprising: receiving an input communication signal atpositive and negative input communication terminals of a receivercircuit from the communication interface circuit; generating ademodulation clock signal at a demodulation clock output of the receivercircuit; generating an input communication data stream at an inputcommunication data stream output of the receiver circuit based on theinput communication signal at the positive and negative inputcommunication terminals and the demodulation clock signal; receiving theinput communication data stream from the receiver circuit at an inputcommunication data stream input of the microcontroller circuit;receiving the demodulation clock signal from the receiver circuit at ademodulation clock input of the microcontroller circuit; processing theinput communication data stream at the microcontroller circuit using thedemodulation clock signal to detect modulated data carried by the inputcommunication signal and represented within the input communication datastream; and generating the transmit select signal at the microcontrollercircuit in response to detecting, for a predetermined time, an absenceof the modulated data in the input communication data streamrepresenting the input communication signal.
 16. The method of claim 15,further comprising: generating a permission to operate (PTO) signal at aPTO output of the microcontroller circuit in response to detecting apresence of modulated data carried by the input communication signal andrepresented within the input communication data stream that isrepresentative of a keep alive command associated with the PV module;generating a local PTO signal at a local PTO output terminal of a PTOdistribution circuit based on the PTO signal at a PTO input; andgenerating a remote PTO signal at a remote PTO output terminal of a PTOdistribution circuit based on the PTO signal.
 17. The method of claim15, wherein the receiver circuit includes a bandpass filter circuit, acrystal oscillator circuit, and an analog-to-digital converter circuit,the method further comprising: generating a filtered input waveform at afiltered input communication output of the bandpass filter circuit basedon the input communication signal at positive and negative inputcommunication terminals; generating the demodulation clock signal at ademodulation clock output of the crystal oscillator circuit; andgenerating the input communication data stream at an input communicationdata stream output of the analog-to-digital converter circuit based onthe filtered input waveform at a filtered input communication input inresponse to the demodulation clock signal at a second demodulation clockinput; wherein the positive and negative input communication terminalsof the receiver circuit include the positive and negative inputcommunication terminals of the bandpass filter circuit, wherein thedemodulation clock output of the receiver circuit includes thedemodulation clock output of the crystal oscillator circuit, wherein theinput communication data stream output of the receiver circuit includesthe input communication data stream output of the analog-to-digitalconverter circuit.
 18. The method of claim 14, wherein the measurementconditioning circuit includes a voltage measurement conditioning circuitand an analog-to-digital converter circuit, the method furthercomprising: receiving the sensed voltage signal at a voltage senseterminal of the voltage measurement conditioning circuit from the stringof PV sub-modules; receiving the voltage reference signal at a voltagereference terminal of the voltage measurement conditioning circuit fromthe string of PV sub-modules; generating an analog voltage signal at ananalog voltage output of the voltage measurement conditioning circuitbased on the sensed voltage signal at the voltage sense terminal inreference to the voltage reference signal at the voltage referenceterminal; and generating digital voltage measurement data at a digitalvoltage measurement output of the analog-to-digital converter circuitbased on the analog voltage signal at an analog voltage input such thatthe sensed voltage signal is represented within the digital voltagemeasurement data; wherein the digital measurement data output of themeasurement conditioning circuit includes the digital voltagemeasurement output and the digital measurement data generated by themeasurement conditioning circuit includes the digital voltagemeasurement data, wherein the digital measurement data input of themicrocontroller circuit includes a digital voltage measurement inputcoupled with the digital voltage measurement output.
 19. The method ofclaim 18, wherein the measurement conditioning circuit also includes asecond analog-to-digital converter circuit, the method furthercomprising: receiving a second sensed voltage signal at a second voltagesense terminal of the voltage measurement conditioning circuit from thestring of PV sub-modules; generating a second analog voltage signal at asecond analog voltage output of the voltage measurement conditioningcircuit based on the second sensed voltage signal at the second voltagesense terminal in reference to the voltage reference signal at thevoltage reference terminal; and generating second digital voltagemeasurement data at a second digital voltage measurement output of thesecond analog-to-digital converter circuit based on the second analogvoltage signal at a second analog voltage input such that the secondsensed voltage signal is represented within the second digital voltagemeasurement data; wherein the digital measurement data output of themeasurement conditioning circuit includes the second digital voltagemeasurement output and the digital measurement data generated by themeasurement conditioning circuit includes the second digital voltagemeasurement data, wherein the digital measurement data input of themicrocontroller circuit includes a second digital voltage measurementinput coupled with the second digital voltage measurement output. 20.The method of claim 19, wherein the measurement conditioning circuitalso includes a third analog-to-digital converter circuit, the methodfurther comprising: receiving a third sensed voltage signal at a thirdvoltage sense terminal of the voltage measurement conditioning circuitfrom the string of PV sub-modules; generating a third analog voltagesignal at a third analog voltage output of the voltage measurementconditioning circuit based on the third sensed voltage signal at thethird voltage sense terminal in reference to the voltage referencesignal at the voltage reference terminal; and generating third digitalvoltage measurement data at a third digital voltage measurement outputof the third analog-to-digital converter circuit based on the thirdanalog voltage signal at a third analog voltage input such that thethird sensed voltage signal is represented within the third digitalvoltage measurement data; wherein the digital measurement data output ofthe measurement conditioning circuit includes the third digital voltagemeasurement output and the digital measurement data generated by themeasurement conditioning circuit includes the third digital voltagemeasurement data, wherein the digital measurement data input of themicrocontroller circuit includes a third digital voltage measurementinput coupled with the third digital voltage measurement output.
 21. Themethod of claim 18, wherein the measurement conditioning circuit alsoincludes a current measurement conditioning circuit and a secondanalog-to-digital converter circuit, the method further comprising:receiving a sensed current signal at a positive current sense terminalof the current measurement conditioning circuit from a current sensorassociated with the string of PV sub-modules; receiving a currentreference signal at a negative current sense terminal of the currentmeasurement conditioning circuit from the current sensor; generating ananalog current signal at an analog current output of the currentmeasurement conditioning circuit based on the sensed current signal atthe positive current sense terminal in reference to the currentreference signal at the negative current sense terminal; and generatingdigital current measurement data at a digital current measurement outputof the second analog-to-digital converter circuit based on the analogcurrent signal at an analog current input such that the sensed currentsignal is represented within the digital current measurement data;wherein the digital measurement data output of the measurementconditioning circuit includes the digital current measurement output andthe digital measurement data generated by the measurement conditioningcircuit includes the digital current measurement data, wherein thedigital measurement data input of the microcontroller circuit includes adigital current measurement input coupled with the digital currentmeasurement output.
 22. The method of claim 21, further comprising:generating power measurement data associated with the string of PVsub-modules at the microcontroller circuit based on the digital voltagemeasurement data associated with the sensed voltage signal and thedigital current measurement data associated with the sensed currentsignal, wherein the measurement data stream is also based on the powermeasurement data such that the power measurement data is representedwithin the measurement data stream and the output communication signal.23. The method of claim 21, wherein the measurement conditioning circuitalso includes a third analog-to-digital converter circuit, the methodfurther comprising: receiving a second sensed current signal at a secondpositive current sense terminal of the current measurement conditioningcircuit from a second current sensor associated with the string of PVsub-modules; receiving a second current reference signal at a secondnegative current sense terminal of the current measurement conditioningcircuit from the second current sensor; generating a second analogcurrent signal at a second analog current output of the currentmeasurement conditioning circuit based on the second sensed currentsignal at the second positive current sense terminal in reference to thesecond current reference signal at the second negative current senseterminal; and generating second digital current measurement data at asecond digital current measurement output of the third analog-to-digitalconverter circuit based on the second analog current signal at a secondanalog current input such that the second sensed current signal isrepresented within the second digital current measurement data; whereinthe digital measurement data output of the measurement conditioningcircuit includes the second digital current measurement output and thedigital measurement data generated by the measurement conditioningcircuit includes the second digital current measurement data, whereinthe digital measurement data input of the microcontroller circuitincludes a second digital current measurement input coupled with thesecond digital current measurement output.
 24. The method of claim 18,wherein the measurement conditioning circuit also includes a temperaturemeasurement conditioning circuit and a second analog-to-digitalconverter circuit, the method further comprising: receiving a sensedtemperature signal at a positive temperature sense terminal of thetemperature measurement conditioning circuit from a temperature sensorassociated with the string of PV sub-modules; receiving a temperaturereference signal at a negative temperature sense terminal of thetemperature measurement conditioning circuit from the temperaturesensor; generating an analog temperature signal at an analog temperatureoutput of the temperature measurement conditioning circuit based on thesensed temperature signal at the positive temperature sense terminal inreference to the temperature reference signal at the negativetemperature sense terminal; and generating digital temperaturemeasurement data at a digital temperature measurement output of thesecond analog-to-digital converter circuit based on the analogtemperature signal at an analog temperature input such that the sensedtemperature signal is represented within the digital temperaturemeasurement data; wherein the digital measurement data output of themeasurement conditioning circuit includes the digital temperaturemeasurement output and the digital measurement data generated by themeasurement conditioning circuit includes the digital temperaturemeasurement data, wherein the digital measurement data input of themicrocontroller circuit includes a digital temperature measurement inputcoupled with the digital temperature measurement output.
 25. The methodof claim 14, wherein the measurement conditioning circuit includes avoltage measurement conditioning circuit, a current measurementconditioning circuit, a temperature measurement conditioning circuit, amultiplexer circuit, and an analog-to-digital converter circuit, themethod further comprising: receiving the sensed voltage signal at avoltage sense terminal of the voltage measurement conditioning circuitfrom the string of PV sub-modules; receiving a second sensed voltagesignal at a second voltage sense terminal of the voltage measurementconditioning circuit from the string of PV sub-modules; receiving athird sensed voltage signal at a third voltage sense terminal of thevoltage measurement conditioning circuit from the string of PVsub-modules; receiving the voltage reference signal at a voltagereference terminal of the voltage measurement conditioning circuit fromthe string of PV sub-modules; generating an analog voltage signal at ananalog voltage output of the voltage measurement conditioning circuitbased on the sensed voltage signal at the voltage sense terminal inreference to the voltage reference signal at the voltage referenceterminal; generating a second analog voltage signal at a second analogvoltage output of the voltage measurement conditioning circuit based onthe second sensed voltage signal at the second voltage sense terminal inreference to the voltage reference signal at the voltage referenceterminal; generating a third analog voltage signal at a third analogvoltage output of the voltage measurement conditioning circuit based onthe third sensed voltage signal at the third voltage sense terminal inreference to the voltage reference signal at the voltage referenceterminal; receiving a first sensed current signal at a first positivecurrent sense terminal of the current measurement conditioning circuitfrom a first current sensor associated with the string of PVsub-modules; receiving a first current reference signal at a firstnegative current sense terminal of the current measurement conditioningcircuit from the first current sensor; receiving a second sensed currentsignal at a second positive current sense terminal of the currentmeasurement conditioning circuit from a second current sensor associatedwith the string of PV sub-modules; receiving a second current referencesignal at a second negative current sense terminal of the currentmeasurement conditioning circuit from the second current sensor;generating a first analog current signal at a first analog currentoutput of the current measurement conditioning circuit based on thefirst sensed current signal at the first positive current sense terminalin reference to the first current reference signal at the first negativecurrent sense terminal; generating a second analog current signal at asecond analog current output of the current measurement conditioningcircuit based on the second sensed current signal at the second positivecurrent sense terminal in reference to the second current referencesignal at the second negative current sense terminal; receiving a sensedtemperature signal at a positive temperature sense terminal of thetemperature measurement conditioning circuit from a temperature sensorassociated with the string of PV sub-modules; receiving a temperaturereference signal at a negative temperature sense terminal of thetemperature measurement conditioning circuit from the temperaturesensor; generating an analog temperature signal at an analog temperatureoutput of the temperature measurement conditioning circuit based on thesensed temperature signal at the positive temperature sense terminal inreference to the temperature reference signal at the negativetemperature sense terminal; receiving the analog voltage signal at ananalog voltage input of the multiplexer circuit; receiving the secondanalog voltage signal at a second analog voltage input of themultiplexer circuit; receiving the third analog voltage signal at athird analog voltage input of the multiplexer circuit; receiving thefirst analog current signal at a first analog current input of themultiplexer circuit; receiving the second analog current signal at asecond analog current input of the multiplexer circuit; receiving theanalog temperature signal at an analog temperature input of themultiplexer circuit; generating a measurement select signal at ameasurement select output of the microcontroller circuit to enableselection of a select analog signal from multiple analog signalsreceived at multiple analog inputs to the multiplexer circuit forrouting the select analog signal to an analog measurement output;receiving the measurement select signal at a measurement select input ofthe multiplexer circuit; routing the analog voltage input, the secondanalog voltage input, the third analog voltage input, the first analogcurrent input, the second analog current input, or the analogtemperature input to the analog measurement output in response to themeasurement select signal at the measurement select input to provide ananalog measurement signal to the analog measurement output; andgenerating the digital measurement data at a digital measurement dataoutput of the analog-to-digital converter circuit based on the analogmeasurement signal at an analog measurement input.
 26. The method ofclaim 14, wherein the transmitter circuit includes a crystal oscillatorcircuit, a digital-to-analog converter circuit, a modulator circuit, anda power amplifier circuit, the method further comprising: generating themodulation clock signal at a modulation clock output of the crystaloscillator circuit; generating an analog measurement signal at an analogmeasurement output of the digital-to-analog converter circuit based onthe measurement data stream at a measurement data stream input inresponse to the modulation clock signal at a second modulation clockinput; generating a modulated measurement signal at a modulatedmeasurement output of the modulator circuit based on the analogmeasurement signal at an analog measurement input in response to themodulation clock signal at a modulation clock input; generating theoutput communication signal at the power amplifier circuit based on themodulated measurement signal at a third modulated measurement input; andtransmitting the output communication signal to the communicationinterface circuit via positive and negative output communicationterminals of the power amplifier circuit in response to the transmitselect signal at a transmit select input; wherein the modulation clockoutput of the transmitter circuit includes the modulation clock outputof the crystal oscillator circuit, wherein the measurement data streaminput of the transmitter circuit includes the measurement data streaminput of the digital-to-analog converter circuit, wherein the positiveand negative output communication terminals of the transmitter circuitinclude the positive and negative output communication terminals of thepower amplifier circuit, wherein the transmit select input of thetransmitter circuit includes the transmit select input of the poweramplifier circuit.
 27. A photovoltaic (PV) module, comprising: acommunication interface circuit, including positive and negative inputcommunication terminals and an external interface; a first PVsub-module, including positive and negative DC power terminals; a secondPV sub-module, including a positive DC power terminal coupled with thenegative DC power terminal of the first PV sub-module and a negative DCpower terminal; a third PV sub-module, including a positive DC powerterminal coupled with the negative DC power terminal of the second PVsub-module and a negative DC power terminal; and a monitoring circuit,including positive and negative output communication terminals coupledwith the positive and negative input communication terminals, a voltagesense terminal coupled with the positive DC power terminal of the firstPV sub-module, and a voltage reference terminal coupled with thenegative DC power terminal of the third PV sub-module.
 28. The PV moduleof claim 27, wherein the monitoring circuit also includes a secondvoltage sense terminal coupled with the positive DC power terminal ofthe second PV sub-module, wherein the monitoring circuit also includes athird voltage sense terminal coupled with the positive DC power terminalof the third PV sub-module.
 29. The PV module of claim 27, furthercomprising: a current sensor, including positive and negative terminals;wherein the monitoring circuit includes a positive current senseterminal coupled with the positive terminal and a negative current senseterminal coupled with the negative terminal.
 30. The PV module of claim27, further comprising: a temperature sensor, including positive andnegative terminals; wherein the monitoring circuit includes a positivetemperature sense terminal coupled with the positive terminal and anegative temperature sense terminal coupled with the negative terminal.